Quaternized nitrogen compounds and use thereof as additives in fuels and lubricants

ABSTRACT

The present invention relates to novel quaternized nitrogen compounds, to the preparation thereof and to the use thereof as a fuel and lubricant additive, more particularly as a detergent additive; to additive packages which comprise these compounds; and to fuels and lubricants thus additized. The present invention further relates to the use of these quaternized nitrogen compounds as a fuel additive for reducing or preventing deposits in the injection systems of direct-injection diesel engines, especially in common-rail injection systems, for reducing the fuel consumption of direct-injection diesel engines, especially of diesel engines with common-rail injection systems, and for minimizing power loss in direct-injection diesel engines, especially in diesel engines with common-rail injection systems.

The present invention relates to novel quaternized nitrogen compounds,to the preparation thereof and to the use thereof as a fuel andlubricant additive, more particularly as a detergent additive, toadditive packages which comprise these compounds; and to fuels andlubricants thus additized. The present invention further relates to theuse of these quaternized nitrogen compounds as a fuel additive forreducing or preventing deposits in the injection systems ofdirect-injection diesel engines, especially in common-rail injectionsystems, for reducing the fuel consumption of direct-injection dieselengines, especially of diesel engines with common-rail injectionsystems, and for minimizing power loss in direct-injection dieselengines, especially in diesel engines with common-rail injectionsystems.

STATE OF THE ART

In direct-injection diesel engines, the fuel is injected and distributedultrafinely (nebulized) by a multihole injection nozzle which reachesdirectly into the combustion chamber of the engine, instead of beingintroduced into a prechamber or swirl chamber as in the case of theconventional (chamber) diesel engine. The advantage of thedirect-injection diesel engines lies in their high performance fordiesel engines and nevertheless low fuel consumption. Moreover, theseengines achieve a very high torque even at low speeds.

At present, essentially three methods are being used to inject the fueldirectly into the combustion chamber of the diesel engine: theconventional distributor injection pump, the pump-nozzle system(unit-injector system or unit-pump system) and the common-rail system.

In the common-rail system, the diesel fuel is conveyed by a pump withpressures up to 2000 bar into a high-pressure line, the common rail.Proceeding from the common rail, branch lines run to the differentinjectors which inject the fuel directly into the combustion chamber.The full pressure is always applied to the common rail, which enablesmultiple injection or a specific injection form. In the other injectionsystems, in contrast, only smaller variation in the injection ispossible. The injection in the common rail is divided essentially intothree groups: (1.) pre-injection, by which essentially softer combustionis achieved, such that harsh combustion noises (“nailing”) are reducedand the engine seems to run quietly; (2.) main injection, which isresponsible especially for a good torque profile; and (3.)post-injection, which especially ensures a low NO_(x) value. In thispost-injection, the fuel is generally not combusted, but insteadevaporated by residual heat in the cylinder. The exhaust gas/fuelmixture formed is transported to the exhaust gas system, where the fuel,in the presence of suitable catalysts, acts as a reducing agent for thenitrogen oxides NO_(x).

The variable, cylinder-individual injection in the common-rail injectionsystem can positively influence the pollutant emission of the engine,for example the emission of nitrogen oxides (NO_(x)), carbon monoxide(CO) and especially of particulates (soot). This makes it possible, forexample, that engines equipped with common-rail injection systems canmeet the Euro 4 standard theoretically even without additionalparticulate filters.

In modern common-rail diesel engines, under particular conditions, forexample when biodiesel-containing fuels or fuels with metal impuritiessuch as zinc compounds, copper compounds, lead compounds and other metalcompounds are used, deposits can form on the injector orifices, whichadversely affect the injection performance of the fuel and hence impairthe performance of the engine, i.e. especially reduce the power, but insome cases also worsen the combustion. The formation of deposits isenhanced further by further developments in the injector construction,especially by the change in the geometry of the nozzles (narrower,conical orifices with rounded outlet). For lasting optimal functioningof engine and injectors, such deposits in the nozzle orifices must beprevented or reduced by suitable fuel additives.

In the injection systems of modern diesel engines, deposits causesignificant performance problems. It is common knowledge that suchdeposits in the spray channels can lead to a decrease in the fuel flowand hence to power loss. Deposits at the injector tip, in contrast,impair the optimal formation of fuel spray mist and, as a result, causeworsened combustion and associated higher emissions and increased fuelconsumption. In contrast to these conventional “external” depositionphenomena, “internal” deposits (referred to collectively as internaldiesel injector deposits (IDID)) in particular parts of the injectors,such as at the nozzle needle, at the control piston, at the valvepiston, at the valve seat, in the control unit and in the guides ofthese components, also increasingly cause performance problems.Conventional additives exhibit inadequate action against these IDIDs.

U.S. Pat. No. 4,248,719 describes quaternized ammonium salts which areprepared by reacting an alkenylsuccinimide with a monocarboxylic esterand find use as dispersants in lubricant oils for prevention of sludgeformation. More particularly, for example, the reaction ofpolyisobutylsuccinic anhydride (PIBSA) with N,N-dimethylaminopropylamine(DMAPA) and quaternization with methyl salicylate is described. However,use in fuels, more particularly diesel fuels, is not proposed therein.The use of PIBSA with low bismaleation levels of <20% is not describedtherein.

U.S. Pat. No. 4,171,959 describes quaternized ammonium salts ofhydrocarbyl-substituted succinimides, which are suitable as detergentadditives for gasoline fuel compositions. For quaternization, preferenceis given to using alkyl halides. Also mentioned are organicC₂-C₈-hydrocarbyl carboxylates and sulfonates. Consequently, thequaternized ammonium salts provided according to the teaching thereinhave, as a counterion, either a halide or a C₂-C₈-hydrocarbylcarboxylate or a C₂-C₈-hydrocarbyl sulfonate group. The use of PIBSAwith low bismaleation levels of <20% is likewise not described therein.

EP-A-2 033 945 discloses cold flow improvers which are prepared byquaternizing specific tertiary monoamines bearing at least oneC₈-C₄₀-alkyl radical with a C₁-C₄-alkyl ester of specific carboxylicacids. Examples of such carboxylic esters are dimethyl oxalate, dimethylmaleate, dimethyl phthalate and dimethyl fumarate. Applications otherthan that of improving the CFPP value of middle distillates are notdemonstrated in EP-A-2 033 945.

WO 2006/135881 describes quaternized ammonium salts prepared bycondensation of a hydrocarbyl-substituted acylating agent and of anoxygen or nitrogen atom-containing compound with a tertiary amino group,and subsequent quaternization by means of hydrocarbyl epoxide in thepresence of stoichiometric amounts of an acid, especially acetic acid.Further quaternizing agents claimed in WO 2006/135881 are dialkylsulfates, benzyl halides and hydrocarbyl-substituted carbonates, anddimethyl sulfate, benzyl chloride and dimethyl carbonate have beenstudied experimentally.

The quaternizing agents used with preference in WO 2006/135881, however,have serious disadvantages such as: toxicity or carcinogenicity (forexample in the case of dimethyl sulfate and alkylene oxides and benzylhalides), no residue-free combustion (for example in the case ofdimethyl sulfate and alkyl halides), and inadequate reactivity whichleads to incomplete quaternization or uneconomic reaction conditions(long reaction times, high reaction temperatures, excess of quaternizingagent; for example in the case of dimethyl carbonate).

It was therefore an object of the present invention to provide improvedquaternized fuel additives, especially based on hydrocarbyl-substitutedpolycarboxylic acid compounds, which no longer have the disadvantages ofthe prior art mentioned.

BRIEF DESCRIPTION OF THE INVENTION

It has now been found that, surprisingly, the above object is achievedby providing specific quaternized nitrogen compounds and fuel andlubricant compositions additized therewith.

Surprisingly, the inventive additives thus prepared are superior inseveral ways to the prior art additives prepared in a conventionalmanner: they have low toxicity (caused by the specific selection of thequaternizing agent, burn ashlessly, exhibit a high content ofquaternized product, and allow an economic reaction regime in thepreparation thereof, and surprisingly have improved handling properties,such as especially improved solubility, such as especially in dieselperformance additive packages. At the same time, the inventive additivesexhibit improved action with regard to prevention of deposits in dieselengines, as especially illustrated by the use examples appended.

DETAILED DESCRIPTION OF THE INVENTION A1) Specific Embodiments

The present invention relates especially to the following specificembodiments:

1. A fuel or lubricant composition, especially fuel composition,comprising, in a majority of a customary fuel or lubricant, a proportion(especially an effective amount) of at least one reaction productcomprising a quaternized nitrogen compound (or a fraction thereof whichcomprises a quaternized nitrogen compound and is obtained from thereaction product by purification), said reaction product beingobtainable by

a. reacting a high molecular weight hydrocarbyl-substitutedpolycarboxylic acid compound with a compound comprising at least oneoxygen or nitrogen group reactive (especially capable of addition orcondensation) with the polycarboxylic acid, and comprising at least onequaternizable amino group, to obtain a quaternizablehydrocarbyl-substituted polycarboxylic acid compound (by addition orcondensation), and

b. subsequent reaction thereof with a quaternizing agent which convertsthe at least one hereafter quaternizable, for example tertiary, aminogroup to a quaternary ammonium group, said quaternizing agent being thealkyl ester of a cycloaromatic or cycloaliphatic mono- or polycarboxylicacid (especially of a mono- or dicarboxylic acid) or of an aliphaticpolycarboxylic acid (especially dicarboxylic acid).

2. A fuel or lubricant composition, especially fuel composition,comprising, in a majority of a customary fuel or lubricant, a proportion(especially an effective amount) of at least one reaction productcomprising a quaternized nitrogen compound (or a fraction thereof whichcomprises a quaternized nitrogen compound and is obtained from thereaction product by purification), said reaction product beingobtainable by reacting a quaternizable high molecular weighthydrocarbyl-substituted polycarboxylic acid compound comprising at leastone quaternizable amino group with a quaternizing agent which convertsthe at least one hereafter quaternizable, for example tertiary, aminogroup to a quaternary ammonium group,

said quaternizing agent being the alkyl ester of a cycloaromatic orcycloaliphatic mono- or polycarboxylic acid (especially of a mono- ordicarboxylic acid) or of an aliphatic polycarboxylic acid (especiallydicarboxylic acid).

3. The fuel composition according to either of the preceding claims,wherein about 1.1 to about 2.0 or about 1.25 to about 2.0 equivalents,for example 1.3, 1.4, 1.5, 1.6, 1.7, 1.8 or 1.9 equivalents, ofquaternizing agent are used per equivalent of quaternizable tertiarynitrogen atom. By increasing the proportion of quaternizing agent withinthe range claimed, distinct improvements in product yields can beachieved.

4. The fuel composition according to any of the preceding claims,wherein the hydrocarbyl-substituted polycarboxylic acid compound is apolyisobutenylsuccinic acid or an anhydride thereof, said acid having abismaleation level of equal to or less than about 20% or equal to orless than about 15%, for example 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5,4, 3, 2, 1 or 0.1%.

Lower levels of bismaleation can contribute to a distinct improvement inthe solubility of the additive and/or compatibility of the constituentsin the formulation of additive packages.

5. The fuel or lubricant composition, especially fuel composition,according to any of the preceding embodiments, wherein the quaternizingagent is a compound of the general formula 1

R₁OC(O)R₂  (1)

in which

R₁ is a low molecular weight hydrocarbyl radical, such as alkyl oralkenyl radical, especially a lower alkyl radical, such as especiallymethyl or ethyl, and

R₂ is an optionally substituted monocyclic hydrocarbyl radical,especially an aryl or cycloalkyl or cycloalkenyl radical, especiallyaryl such as phenyl, where the substituent is selected from OH, NH₂,NO₂, C(O)OR₃, and R₁OC(O)—, in which R₁ is as defined above and R₃ is Hor R₁, where the substituent is especially OH. More particularly, thequaternizing agent is a phthalate or a salicylate, such as dimethylphthalate or methyl salicylate.

6. The fuel or lubricant composition, especially fuel composition,according to any of the preceding embodiments, wherein the quaternizingagent is a compound of the general formula 2

R₁OC(O)-A-C(O)OR_(1a)  (2)

in which

R₁ and R_(1a) are each independently a low molecular weight hydrocarbylradical, such as an alkyl or alkenyl radical, especially a lower alkylradical and

A is hydrocarbylene (such as especially C₁-C₇-alkylene orC₂-C₇-alkenylene).

7. The fuel or lubricant composition, especially fuel composition,according to any of the preceding embodiments, wherein the quaternizednitrogen compound has a number-average molecular weight in the rangefrom 400 to 5000, especially 800 to 3000 or 900 to 1500.

8. The fuel or lubricant composition, especially fuel composition,according to any of the preceding embodiments, wherein the quaternizingagent is selected from alkyl salicylates, dialkyl phthalates and dialkyloxalates; particular mention should be made of alkyl salicylates,especially lower alkyl salicylates, such as methyl, ethyl and n-propylsalicylates.

9. The fuel or lubricant composition, especially fuel composition,according to embodiment 1, wherein the compound which is reactive(capable of addition or condensation) with the polycarboxylic acid andcomprises an oxygen or nitrogen group and at least one quaternizableamino group is selected from

a. hydroxyalkyl-substituted mono- or polyamines having at least onequaternizable primary, secondary or tertiary amino group;

b. straight-chain or branched, cyclic, heterocyclic, aromatic ornonaromatic polyamines having at least one primary or secondary aminogroup and having at least one quaternizable primary, secondary ortertiary amino group;

c. piperazines,

and particular mention should be made of group a.

10. The fuel or lubricant composition according to embodiment 9, whereinthe compound which is reactive, especially capable of addition orcondensation, with the polycarboxylic acid and comprises an oxygen ornitrogen group and at least one quaternizable amino group is selectedfrom

a. hydroxyalkyl-substituted primary, secondary or tertiary monoaminesand hydroxyalkyl-substituted primary, secondary or tertiary diamines,

b. straight-chain or branched aliphatic diamines having two primaryamino groups; di- or polyamines having at least one primary and at leastone secondary amino group; di- or polyamines having at least one primaryand at least one tertiary amino group; aromatic carbocyclic diamineshaving two primary amino groups; aromatic heterocyclic polyamines havingtwo primary amino groups; aromatic or nonaromatic heterocycles havingone primary and one tertiary amino group; and particular mention shouldbe made of group a.

11. The fuel composition according to any of the preceding embodiments,selected from diesel fuels, biodiesel fuels, gasoline fuels andalkanol-containing gasoline fuels.

12. The fuel or lubricant composition, especially fuel composition,according to any of the preceding embodiments, wherein thehydrocarbyl-substituted polycarboxylic acid compound is apolyisobutenylsuccinic acid or an anhydride (PIBSA) thereof, said acidhaving a low bismaleation level, especially 10% or less than 10%, forexample 2 to 9 or 3 to 7%. More particularly, such PIBSAs are derivedfrom HR-PIB with an Mn in the range from about 400 to 3000.

More particularly, the above compositions are fuel compositions, inparticular diesel fuels.

13. The reaction product obtainable by a process as defined in any ofthe preceding embodiments, especially according to embodiment 3, 4, 5, 6and in particular embodiment 8, 9 or 10, or quaternized nitrogencompound obtained from the reaction product by partial or fullpurification.

In a particular configuration (A) of the invention, quaternized reactionproducts which are prepared proceeding from polyisobutenylsuccinic acidor an anhydride thereof are provided, this compound having abismaleation level of equal to or less than about 20% or equal to orless than about 15%, for example 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5,4, 3, 2, 1, or 0.1%. This polyisobutenylsuccinic acid compound isreacted (especially by addition or condensation) with a compoundcomprising at least one oxygen or nitrogen group reactive (addable orcondensable) with the polyisobutenylsuccinic acid compound andcontaining at least one quaternizable amino group, and then quaternized.

In a particular configuration (B) of the invention, quaternized reactionproducts which are obtained by quaternization using an excess ofquaternizing agent are provided. More particularly, about 1.1 to about2.0 or about 1.25 to about 2.0 equivalents, for example 1.3, 1.4, 1.5,1.6, 1.7, 1.8 or 1.9, equivalents of quaternizing agent are used perequivalent of quaternizable tertiary nitrogen atoms. Particularly usefulquaternizing agents are those of the formula (1), especially the loweralkyl esters of salicylic acid, such as methyl salicylate, ethylsalicylate, n- and i-propyl salicylate, and n-, i- or tert-butylsalicylate.

In a further particular configuration (C), configurations (A) and (B)are combined, i.e. the quaternizable compounds prepared from the abovepolyisobutenylsuccinic acid compounds according to configuration (A) arequaternized according to configuration (B).

14. A process for preparing a quaternized nitrogen compound according toembodiment 13,

comprising the reaction of a quaternizable hydrocarbyl-substitutedpolycarboxylic acid compound comprising at least one tertiaryquaternizable amino group with a quaternizing agent which converts theat least one tertiary amino group to a quaternary ammonium group,

said quaternizing agent being the alkyl ester of a cycloaromatic orcycloaliphatic mono- or polycarboxylic acid (especially of a mono- ordicarboxylic acid) or of an aliphatic polycarboxylic acid (especiallydicarboxylic acid).

15. The use of a reaction product or of a quaternized nitrogen compoundaccording to embodiment 13 or of a compound prepared according toembodiment 14 as a fuel additive or lubricant additive, especially fueladditive, especially diesel fuel additive.

16. The use according to embodiment 15 as an additive for reducing thefuel consumption of direct-injection diesel engines, especially ofdiesel engines with common-rail injection systems, as determined, forexample, in an XUD9 test to CEC-F-23-01, and/or for minimizing powerloss in direct-injection diesel engines, especially in diesel engineswith common-rail injection systems, as determined, for example, in aDW10 test based on CEC-F-098-08.

17. The use according to embodiment 15 as a gasoline fuel additive forreducing the level of deposits in the intake system of a gasolineengine, such as especially DISI (direct injection spark ignition) andPFI (port fuel injector) engines.

18. The use according to embodiment 15 as a diesel fuel additive,especially as a cold flow improver, as a wax antisettling additive(WASA) or as an additive for reducing the level of and/or preventingdeposits in the intake systems, such as especially the internal dieselinjector deposits (IDIDs), and/or valve sticking in direct-injectiondiesel engines, especially in common-rail injection systems.

19. An additive concentrate comprising, in combination with furtherdiesel fuel or gasoline fuel additives, especially diesel fueladditives, at least one quaternized nitrogen compound as defined inembodiment 13 or prepared according to embodiment 14.

A2) General Definitions

A “condensation” or “condensation reaction” in the context of thepresent invention describes the reaction of two molecules withelimination of a relatively small molecule, especially of a watermolecule. When such an elimination is not detectable analytically, moreparticularly not detectable in stoichiometric amounts, and the twomolecules react nevertheless, for example with addition, the reaction inquestion of the two molecules is “without condensation”.

In the absence of statements to the contrary, the following generalconditions apply:

“Hydrocarbyl” can be interpreted widely and comprises both long-chainand short-chain, straight-chain and branched hydrocarbon radicals, whichmay optionally additionally comprise heteroatoms, for example O, N, NH,S, in the chain thereof.

“Long-chain” or “high molecular weight” hydrocarbyl radicals have anumber-average molecular weight (M_(n)) of 85 to 20 000, for example 113to 10 000, or 200 to 10 000 or 350 to 5000, for example 350 to 3000, 500to 2500, 700 to 2500, or 800 to 1500. More particularly, they are formedessentially from C₂₋₆, especially C₂₋₄, monomer units such as ethylene,propylene, n- or isobutylene or mixtures thereof, where the differentmonomers may be copolymerized in random distribution or as blocks. Suchlong-chain hydrocarbyl radicals are also referred to as polyalkyleneradicals or poly-C₂₋₆- or poly-C₂₋₄-alkylene radicals. Suitablelong-chain hydrocarbyl radicals and the preparation thereof are alsodescribed, for example, in WO 2006/135881 and the literature citedtherein.

Examples of particularly useful polyalkylene radicals are polyisobutenylradicals derived from “high-reactivity” polyisobutenes (HR-PIB) whichare notable for a high content of terminal double bonds (cf., forexample, also Rath et al., Lubrication Science (1999), 11-2, 175-185).Terminal double bonds are alpha-olefinic double bonds of the type

which are also referred to collectively as vinylidene double bonds.Suitable high-reactivity polyisobutenes are, for example, polyisobuteneswhich have a proportion of vinylidene double bonds of greater than 70mol %, especially greater than 80 mol % or greater than 85 mol %.Preference is given especially to polyisobutenes which have homogeneouspolymer structures. Homogeneous polymer structures are possessedespecially by those polyisobutenes formed from isobutene units to anextent of at least 85% by weight, preferably to an extent of at least90% by weight and more preferably to an extent of at least 95% byweight. Such high-reactivity polyisobutenes preferably have anumber-average molecular weight within the abovementioned range. Inaddition, the high-reactivity polyisobutenes may have a polydispersityin the range from 1.05 to 7, especially of about 1.1 to 2.5, for exampleof less than 1.9 or less than 1.5. Polydispersity is understood to meanthe quotient of weight-average molecular weight Mw divided by thenumber-average molecular weight Mn.

Particularly suitable high-reactivity polyisobutenes are, for example,the Glissopal brands from BASF SE, especially Glissopal® 1000 (Mn=1000),Glissopal® V 33 (Mn=550), Glissopal® 1300 (Mn=1300) and Glissopal® 2300(Mn=2300), and mixtures thereof. Other number-average molecular weightscan be established in a manner known in principle by mixingpolyisobutenes of different number-average molecular weights or byextractive enrichment of polyisobutenes of particular molecular weightranges.

PIBSA is prepared in a manner known in principle by reacting PIB withmaleic anhydride (MAA), in principle forming a mixture of PIBSA andbismaleated PIBSA (BM PIBSA, cf. scheme 1, below), which is generallynot separated but used as such in further reactions. The ratio of thetwo components to one another can be reported via the “bismaleationlevel” (BML). The BML is known per se (see also U.S. Pat. No.5,883,196). The BML can also be determined by the following formula:

BML=100%×[(wt-%(BM PIBSA))/(wt-%(BM PIBSA)+wt-%(PIBSA))]

where wt-% (X) represents the proportion by weight of component X(X=PIBSA or BM PIBSA) in the reaction product of PIB with MSA.

Hydrocarbyl-substituted polycarboxylic acid compound with a “lowbismaleation level”, especially corresponding polyisobutenylsuccinicacids or anhydrides thereof (also referred to overall as PIBSA) areknown from the prior art. Especially advantageous are bismaleationlevels of 20% or less, or 15% or less, for example 14, 13, 12 or 10%; or10% or less, for example 2-9, 3-8, 4-7, 5 or 6%. The controlledpreparation thereof is described, for example, in U.S. Pat. No.5,883,196. Suitable for preparation thereof are especially the abovehigh-reactivity polyisobutenes with an Mn in the range from about 500 to2500, for example 550 to 3000, 1000 to 2000 or 1000 to 1500.

A nonlimiting example of a corresponding PIBSA is Glissopal® SA, derivedfrom HR-PIB (Mn=1000), with a bismaleation level of 9%.

“Short-chain hydrocarbyl” or “low molecular weight hydrocarbyl” isespecially straight-chain or branched alkyl or alkenyl, optionallyinterrupted by one or more, for example 2, 3 or 4, heteroatom groupssuch as —O— or —NH—, or optionally mono- or polysubstituted, for exampledi-, tri- or tetrasubstituted.

“Alkyl” or “lower alkyl” represents especially saturated, straight-chainor branched hydrocarbon radicals having 1 to 4, 1 to 6, 1 to 8, or 1 to10 or 1 to 20, carbon atoms, for example methyl, ethyl, n-propyl,1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl,1,1-dimethylethyl, n-pentyl, 1-methylbutyl, 2-methylbutyl,3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl,1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl,3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl,1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl,3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl,1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl and1-ethyl-2-methylpropyl; and also n-heptyl, n-octyl, n-nonyl and n-decyl,and the singly or multiply branched analogs thereof.

“Hydroxyalkyl” represents especially the mono- or polyhydroxylated,especially monohydroxylated, analogs of the above alkyl radicals, forexample the monohydroxylated analogs of the above straight-chain orbranched alkyl radicals, for example the linear hydroxyalkyl groups witha primary hydroxyl group, such as hydroxymethyl, 2-hydroxyethyl,3-hydroxypropyl, 4-hydroxybutyl.

“Alkenyl” represents mono- or polyunsaturated, especiallymonounsaturated, straight-chain or branched hydrocarbon radicals having2 to 4, 2 to 6, 2 to 8, 2 to 10 or 2 or to 20 carbon atoms and a doublebond in any position, for example C₂-C₆-alkenyl such as ethenyl,1-propenyl, 2-propenyl, 1-methylethenyl, 1-butenyl, 2-butenyl,3-butenyl, 1-methyl-1-propenyl, 2-methyl-1-propenyl,1-methyl-2-propenyl, 2-methyl-2-propenyl, 1-pentenyl, 2-pentenyl,3-pentenyl, 4-pentenyl, 1-methyl-1-butenyl, 2-methyl-1-butenyl,3-methyl-1-butenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl,3-methyl-2-butenyl, 1-methyl-3-butenyl, 2-methyl-3-butenyl,3-methyl-3-butenyl, 1,1-dimethyl-2-propenyl, 1,2-dimethyl-1-propenyl,1,2-dimethyl-2-propenyl, 1-ethyl-1-propenyl, 1-ethyl-2-propenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl,1-methyl-1-pentenyl, 2-methyl-1-pentenyl, 3-methyl-1-pentenyl,4-methyl-1-pentenyl, 1-methyl-2-pentenyl, 2-methyl-2-pentenyl,3-methyl-2-pentenyl, 4-methyl-2-pentenyl, 1-methyl-3-pentenyl,2-methyl-3-pentenyl, 3-methyl-3-pentenyl, 4-methyl-3-pentenyl,1-methyl-4-pentenyl, 2-methyl-4-pentenyl, 3-methyl-4-pentenyl,4-methyl-4-pentenyl, 1,1-dimethyl-2-butenyl, 1,1-dimethyl-3-butenyl,1,2-dimethyl-1-butenyl, 1,2-dimethyl-2-butenyl, 1,2-dimethyl-3-butenyl,1,3-dimethyl-1-butenyl, 1,3-dimethyl-2-butenyl, 1,3-dimethyl-3-butenyl,2,2-dimethyl-3-butenyl, 2,3-dimethyl-1-butenyl, 2,3-dimethyl-2-butenyl,2,3-dimethyl-3-butenyl, 3,3-dimethyl-1-butenyl, 3,3-dimethyl-2-butenyl,1-ethyl-1-butenyl, 1-ethyl-2-butenyl, 1-ethyl-3-butenyl,2-ethyl-1-butenyl, 2-ethyl-2-butenyl, 2-ethyl-3-butenyl,1,1,2-trimethyl-2-propenyl, 1-ethyl-1-methyl-2-propenyl,1-ethyl-2-methyl-1-propenyl and 1-ethyl-2-methyl-2-propenyl.

“Alkylene” represents straight-chain or mono- or polybranchedhydrocarbon bridge groups having 1 to 10 carbon atoms, for exampleC₁-C₇-alkylene groups selected from —CH₂—, —(CH₂)₂—, —(CH₂)₃—,—CH₂—CH(CH₃)—, —CH(CH₃)—CH₂—, (CH₂)₄—, —(CH₂)₂—CH(CH₃)—,—CH₂—CH(CH₃)—CH₂—, (CH₂)₄—, —(CH₂)₅—, —(CH₂)₆, —(CH₂)₇—,—CH(CH₃)—CH₂—CH₂—CH(CH₃)— or —CH(CH₃)—CH₂—CH₂—CH₂—CH(CH₃)— orC₁-C₄-alkylene groups selected from —CH₂—, —(CH₂)₂—, —(CH₂)₃—,—CH₂—CH(CH₃)—, —CH(CH₃)—CH₂—, —(CH₂)₄—, —(CH₂)₂—CH(CH₃)—,—CH₂—CH(CH₃)—CH₂—.

“Alkenylene” represents the mono- or polyunsaturated, especiallymonounsaturated, analogs of the above alkylene groups having 2 to 10carbon atoms, especially C₂-C₇-alkenylenes or C₂-C₄-alkenylenes, such as—CH═CH—, —CH═CH—CH₂—, —CH₂—CH═CH—, —CH═CH—CH₂—CH₂—, —CH₂—CH═CH—CH₂—,—CH₂—CH₂-CH═CH—, —CH(CH₃)—CH═CH—, —CH₂—C(CH₃)═CH—.

“Cyclic hydrocarbyl radicals” comprise especially:

-   -   cycloalkyl: carbocyclic radicals having 3 to 20 carbon atoms,        for example C₃-C₁₂-cycloalkyl such as cyclopropyl, cyclobutyl,        cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl,        cyclodecyl, cycloundecyl and cyclododecyl; preference is given        to cyclopentyl, cyclohexyl, cycloheptyl, and also to        cyclopropylmethyl, cyclopropylethyl, cyclobutylmethyl,        cyclobutylethyl, cyclopentylmethyl, cyclopentylethyl,        cyclohexylmethyl, or C₃-C₇-cycloalkyl such as cyclopropyl,        cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,        cyclopropylmethyl, cyclopropylethyl, cyclobutylmethyl,        cyclopentylethyl, cyclohexylmethyl, where the bond to the rest        of the molecule may be via any suitable carbon atom.    -   cycloalkenyl: monocyclic, monounsaturated hydrocarbon groups        having 5 to 8, preferably up to 6, carbon ring members, such as        cyclopenten-1-yl, cyclopenten-3-yl, cyclohexen-1-yl,        cyclohexen-3-yl and cyclohexen-4-yl;    -   aryl: mono- or polycyclic, preferably mono- or bicyclic,        optionally substituted aromatic radicals having 6 to 20, for        example 6 to 10, ring carbon atoms, for example phenyl,        biphenyl, naphthyl such as 1- or 2-naphthyl, tetrahydronaphthyl,        fluorenyl, indenyl and phenanthrenyl. These aryl radicals may        optionally bear 1, 2, 3, 4, 5 or 6 identical or different        substituents.

“Substituents” for radicals specified herein are especially, unlessstated otherwise, selected from keto groups, —COOH, —COO-alkyl, —OH,—SH, —CN, amino, —NO₂, alkyl, or alkenyl groups.

The term “about” in the context of a stated figure or of a value rangedenotes deviations from the specifically disclosed values. These areusually customary deviations. These may differ, for example, by ±10% to±0.1% from the specific values. Typically, such deviations are about ±8%to ±1% or ±5%, ±4%, ±3% or ±2%.

A3) Polycarboxylic Acid Compounds and Hydrocarbyl-SubstitutedPolycarboxylic Acid Compounds

The polycarboxylic acid compounds used are aliphatic di- or polybasic(for example tri- or tetrabasic), especially from di-, tri- ortetracarboxylic acids and analogs thereof, such as anhydrides or loweralkyl esters (partially or completely esterified), and is optionallysubstituted by one or more (for example 2 or 3), especially a long-chainalkyl radical and/or a high molecular weight hydrocarbyl radical,especially a polyalkylene radical. Examples are C₃-C₁₀ polycarboxylicacids, such as the dicarboxylic acids malonic acid, succinic acid,glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid andsebacic acid, and the branched analogs thereof; and the tricarboxylicacid citric acid; and anhydrides or lower alkyl esters thereof of. Thepolycarboxylic acid compounds can also be obtained from thecorresponding monounsaturated acids and addition of at least onelong-chain alkyl radical and/or high molecular weight hydrocarbylradical. Examples of suitable monounsaturated acids are fumaric acid,maleic acid, itaconic acid.

The hydrophobic “long-chain” or “high molecular weight” hydrocarbylradical which ensures sufficient solubility of the quaternized productin the fuel has a number-average molecular weight (M_(n)) of 85 to 20000, for example 113 to 10 000, or 200 to 10 000 or 350 to 5000, forexample 350 to 3000, 500 to 2500, 700 to 2500, or 800 to 1500. Typicalhydrophobic hydrocarbyl radicals include polypropenyl, polybutenyl andpolyisobutenyl radicals, for example with a number-average molecularweight M_(n) of 3500 to 5000, 350 to 3000, 500 to 2500, 700 to 2500 and800 to 1500.

Suitable hydrocarbyl-substituted compounds are described, for example,in DE 43 19 672 and WO 2008/138836.

Suitable hydrocarbyl-substituted polycarboxylic acid compounds alsocomprise polymeric, especially dimeric, forms of suchhydrocarbyl-substituted polycarboxylic acid compounds. Dimeric formscomprise, for example, two acid anhydride groups which can be reactedindependently with the quaternizable nitrogen compound in thepreparation process according to the invention.

A4) Quaternizing Agents

Useful quaternizing agents are in principle all alkyl esters which aresuitable as such and are those of a cycloaromatic or cycloaliphaticmono- or polycarboxylic acid (especially of a mono- or dicarboxylicacid) or of an aliphatic polycarboxylic acid (especially dicarboxylicacid).

In a particular embodiment, however, the at least one quaternizabletertiary nitrogen atom is quaternized with at least one quaternizingagent selected from

a) Compounds of the General Formula 1

R₁OC(O)R₂  (1)

in which

R₁ is a lower alkyl radical and

R₂ is an optionally substituted monocyclic aryl or cycloalkyl radical,where the substituent is selected from OH, NH₂, NO₂, C(O)OR₃, andR_(1a)OC(O)—, in which R_(1a) is as defined above for R₁ and R₃ is H orR₁;

and

b) Compounds of the General Formula 2

R₁OC(O)-A-C(O)OR_(1a)  (2)

in which

R₁ and R_(1a) are each independently a lower alkyl radical and

A is hydrocarbylene (such as alkylene or alkenylene).

Particularly suitable compounds of the formula 1 are those in which

R₁ is a C₁-, C₂- or C₃-alkyl radical and

R₂ is a substituted phenyl radical, where the substituent is HO— or anester radical of the formula R_(1a)OC(O)— which is in the para, meta orespecially ortho position to the R₁OC(O)— radical on the aromatic ring.

Especially suitable quaternizing agents are the lower alkyl esters ofsalicylic acid, such as methyl salicylate, ethyl salicylate, n- andi-propyl salicylate, and n-, i- or tert-butyl salicylate.

A5) Quaternized or Quaternizable Nitrogen Compounds

The quaternizable nitrogen compounds reactive with the polycarboxylicacid compound are selected from

-   a. hydroxyalkyl-substituted mono- or polyamines having at least one    quaternized (e.g. choline) or quaternizable primary, secondary or    tertiary amino group;-   b. straight-chain or branched, cyclic, heterocyclic, aromatic or    nonaromatic polyamines having at least one primary or secondary    (anhydride-reactive) amino group and having at least one quaternized    or quaternizable primary, secondary or tertiary amino group;-   c. piperazines.

The quaternizable nitrogen compound is especially selected from

-   d. hydroxyalkyl-substituted primary, secondary, tertiary or    quaternary monoamines and hydroxyalkyl-substituted primary,    secondary, tertiary or quaternary diamines;-   e. straight-chain or branched aliphatic diamines having two primary    amino groups; di- or polyamines having at least one primary and at    least one secondary amino group; di- or polyamines having at least    one primary and at least one tertiary amino group; di- or polyamines    having at least one primary and at least one quaternary amino group;    aromatic carbocyclic diamines having two primary amino groups;    aromatic heterocyclic polyamines having two primary amino groups;    aromatic or nonaromatic heterocycles having one primary and one    tertiary amino group.

Examples of suitable “hydroxyalkyl-substituted mono- or polyamines” arethose provided with at least one hydroxyalkyl substituted, for example1, 2, 3, 4, 5 or 6 hydroxyalkyl substituted.

Examples of “hydroxyalkyl-substituted monoamines” include:N-hydroxyalkyl monoamines, N,N-dihydroxyalkyl monoamines andN,N,N-trihydroxyalkyl monoamines, where the hydroxyalkyl groups are thesame or different and are also as defined above. Hydroxyalkyl isespecially 2-hydroxyethyl, 3-hydroxypropyl or 4-hydroxybutyl.

For example, the following “hydroxyalkyl-substituted polyamines” andespecially “hydroxyalkyl-substituted diamines” may be mentioned:(N-hydroxyalkyl)alkylene-diamines, N,N-dihydroxyalkylalkylenediamines,where the hydroxyalkyl groups are the same or different and are also asdefined above. Hydroxyalkyl is especially 2-hydroxyethyl,3-hydroxypropyl or 4-hydroxybutyl; alkylene is especially ethylene,propylene or butylene.

Suitable “diamines” are alkylenediamines, and the N-alkyl-substitutedanalogs thereof, such as N-monoalkylated alkylenediamines and the N,N-or N,N′-dialkylated alkylenediamines. Alkylene is especiallystraight-chain or branched C₁₋₇- or C₁₋₄-alkylene as defined above.Alkyl is especially C₁₋₄-alkyl as defined above. Examples are especiallyethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine,1,4-butylenediamine and isomers thereof, pentanediamine and isomersthereof, hexanediamine and isomers thereof, heptanediamine and isomersthereof, and singly or multiply, for example singly or doubly,C₁-C₄-alkylated, for example methylated, derivatives of theaforementioned diamine compounds such as 3-dimethylamino-1-propylamine(DMAPA), N,N-diethylaminopropylamine and N,N-dimethylamino-ethylamine.

Suitable straight-chain “polyamines” are, for example,dialkylenetriamine, trialkylenetetramine, tetraalkylenepentamine,pentaalkylenehexamine, and the N-alkyl-substituted analogs thereof, suchas N-monoalkylated and the N,N- or N,N′-dialkylated alkylenepolyamines.Alkylene is especially straight-chain or branched C₁₋₇- or C₁₋₄-alkyleneas defined above. Alkyl is especially C₁₋₄-alkyl as defined above.

Examples are especially diethylenetriamine, triethylenetetramine,tetraethylenepentamine, pentaethylenehexamine, dipropylenetriamine,tripropylenetetramine, tetrapropylenepentamine, pentapropylenehexamine,dibutylenetriamine, tributylenetetramine, tetrabutylenepentamine,pentabutylenehexamine; and the N,N-dialkyl derivatives thereof,especially the N,N-di-C₁₋₄-alkyl derivatives thereof. Examples include:N,N-dimethyldimethylenetriamine, N,N-diethyldimethylenetriamine,N,N-dipropyldimethylenetriamine, N,N-dimethyldiethylene-1,2-triamine,N,N-diethyldiethylene-1,2-triamine, N,N-dipropyldiethylene-1,2-triamine,N,N-dimethyldipropylene-1,3-triamine (i.e. DMAPAPA),N,N-diethyldipropylene-1,3-triamine,N,N-dipropyldipropylene-1,3-triamine,N,N-dimethyldibutylene-1,4-triamine, N,N-diethyldibutylene-1,4-triamine,N,N-dipropyldibutylene-1,4-triamine,N,N-dimethyldipentylene-1,5-triamine,N,N-diethyldipentylene-1,5-triamine,N,N-dipropyldipentylene-1,5-triamine,N,N-dimethyldihexylene-1,6-triamine, N,N-diethyldihexylene-1,6-triamineand N,N-dipropyldihexylene-1,6-triamine.

“Aromatic carbocyclic diamines” having two primary amino groups are thediamino-substituted derivatives of benzene, biphenyl, naphthalene,tetrahydronaphthalene, fluorene, indene and phenanthrene.

“Aromatic or nonaromatic heterocyclic polyamines” having two primaryamino groups are the derivatives, substituted by two amino groups, ofthe following heterocycles:

-   -   5- or 6-membered, saturated or monounsaturated heterocycles        comprising one to two nitrogen atoms and/or one oxygen or sulfur        atom or one or two oxygen and/or sulfur atoms as ring members,        for example tetrahydrofuran, pyrrolidine, isoxazolidine,        isothiazolidine, pyrazolidine, oxazolidine, thiazolidine,        imidazolidine, pyrroline, piperidine, piperidinyl, 1,3-dioxane,        tetrahydropyran, hexahydropyridazine, hexahydropyrimidine,        piperazine;    -   5-membered aromatic heterocycles comprising, in addition to        carbon atoms, two or three nitrogen atoms or one or two nitrogen        atoms and one sulfur or oxygen atom as ring members, for example        furan, thiane, pyrrole, pyrazole, oxazole, thiazole, imidazole        and 1,3,4-triazole; isoxazole, isothiazole, thiadiazole,        oxadiazole;    -   6-membered heterocycles comprising, in addition to carbon atoms,        one or two, or one, two or three, nitrogen atoms as ring        members, for example pyridinyl, pyridazine, pyrimidine,        pyrazinyl, 1,2,4-triazine, 1,3,5-triazin-2-yl.

“Aromatic or nonaromatic heterocycles having one primary and onetertiary amino group” are, for example, the abovementionedN-heterocycles which are aminoalkylated on at least one ring nitrogenatom, and especially bear an amino-C₁₋₄-alkyl group.

“Aromatic or nonaromatic heterocycles having a tertiary amino group anda hydroxyalkyl group” are, for example, the abovementionedN-heterocycles which are hydroxyalkylated on at least one ring nitrogenatom, and especially bear a hydroxy-C₁₄-alkyl group.

Mention should be made especially of the following groups of individualclasses of quaternizable nitrogen compounds:

Group 1:

NAME FORMULA Diamines with primary second nitrogen atom Ethylenediamine

1,2-Propylenediamine

1,3-Propylenediamine

Isomeric butylenediamines, for example

1,5-Pentylenediamine

Isomeric pentanediamines, for example

Isomeric hexanediamines, for example

Isomeric heptanediamines, for example

Di- and polyamines with a secondary second nitrogen atomDiethylenetriamine (DETA)

Dipropylenetriamine (DPTA), 3,3′- iminobis(N,N-dimethylpropylamine)

Triethylenetetramine (TETA)

Tetraethylenepentamine (TEPA)

Pentaethylenehexamine

N-Methyl-3-amino-1-propylamine

Bishexamethylenetriamine

Aromatics Diaminobenzenes, for example

Diaminopyridines, for example

Group 2:

NAME FORMULA Heterocycles 1-(3-Aminopropyl)imidazole

4-(3-Aminopropyl)morpholine

1-(2-Aminoethylpiperidine)

2-(1-Piperazinyl)ethylamine (AEP)

N-Methylpiperazine

Amines with a tertiary second nitrogen atom3,3-Diamino-N-methyldipropyl- amine

3-Dimethylamino-1-propylamine (DMAPA)

N,N-Diethylaminopropylamine

N,N-Dimethylaminoethylamine

Group 3:

NAME FORMULA Alcohols with a primary and secondary amine Ethanolamine

3-Hydroxy-1-propylamine

Diethanolamine

Diisopropanolamine

N-(2-Hydroxyethyl)ethylenediamine

Alcohols with a tertiary amine Triethanolamine, (2,2′,2″-Nitrilotri-ethanol)

1-(3-Hydroxypropyl)imidazole

Tris(hydroxymethyl)amine

3-Dimethylamino-1-propanol

3-Diethylamino-1-propanol

2-Dimethylamino-1-ethanol

4-Diethylamino-1-butanol

A6) Preparation of Inventive Additives

a) Reaction with Oxygen or Nitrogen Group

The hydrocarbyl-substituted polycarboxylic acid compound can be reactedwith the quaternizable nitrogen compound according to the presentinvention under thermally controlled conditions, such that there isessentially no condensation reaction. More particularly, no formation ofwater of reaction is observed in that case. More particularly, such areaction is effected at a temperature in the range from 10 to 80° C.,especially 20 to 60° C. or 30 to 50° C. The reaction time may be in therange from a few minutes or a few hours, for example about 1 minute upto about 10 hours. The reaction can be effected at a pressure of about0.1 to 2 atm, but especially at approximately standard pressure. Forexample, an inert gas atmosphere, for example nitrogen, is appropriate.

More particularly, the reaction can also be effected at elevatedtemperatures which promote condensation, for example in the range from90 to 100° C. or 100 to 170° C.

The reaction time may be in the region of a few minutes or a few hours,for example about 1 minute up to about 10 hours. The reaction can beeffected at pressure at about 0.1 to 2 atm, but especially at aboutstandard pressure.

The reactants are initially charged especially in about equimolaramounts; optionally, a small molar excess of the polycarboxylic acidcompound, for example a 0.05- to 0.5-fold, for example a 0.1- to0.3-fold, excess, is desirable. If required, the reactants can beinitially charged in a suitable inert organic aliphatic or aromaticsolvent or a mixture thereof. Typical examples are, for example,solvents of the Solvesso series, toluene or xylene. The solvent can alsoserve, for example, to remove water of condensation azeotropically fromthe reaction mixture. More particularly, however, the reactions areperformed without solvent.

The reaction product thus formed can theoretically be purified further,or the solvent can be removed. Usually, however, this is not absolutelynecessary, such that the reaction step can be transferred withoutfurther purification into the next synthesis step, the quaternization.

b) Quaternization

The quaternization in reaction step (b) is then carried out in a mannerknown per se.

To perform the quaternization, the reaction product or reaction mixturefrom stage a) is admixed with at least one compound of the above formula1 or 2, especially in the stoichiometric amounts required to achieve thedesired quaternization. It is possible to use, for example, 0.1 to 2.0,0.2 to 1.5 or 0.5 to 1.25 equivalents, of quaternizing agent perequivalent of quaternizable tertiary nitrogen atom. More particularly,however, approximately equimolar proportions of the compound are used toquaternize a tertiary amine group. Correspondingly higher use amountsare required to quaternize a secondary or primary amine group. In afurther variant, the quaternizing agent is added in excess, for example1.1 to 2.0, 1.25 to 2 or 1.25 to 1.75 equivalents of quaternizing agentper equivalent of quaternizable tertiary nitrogen atom.

Typical working temperatures here are in the range from 50 to 180° C.,for example from 90 to 160° C. or 100 to 140° C. The reaction time maybe in the range of a few minutes or a few hours, for example about 10minutes up to about 24 hours. The reaction can be effected at a pressureof about 0.1 to 20 bar, for example 1 to 10 or 1.5 to 3 bar, butespecially at about standard pressure.

If required, the reactants can be initially charged for thequaternization in a suitable inert organic aliphatic or aromatic solventor a mixture thereof, or a sufficient proportion of solvent fromreaction step a) is still present. Typical examples are, for example,solvents of the Solvesso series, toluene or xylene. The quaternizationcan, however, also be performed in the absence of a solvent.

To perform the quaternization, the addition of catalytically activeamounts of an acid may be appropriate. Preference is given to aliphaticmonocarboxylic acids, for example C₁-C₁₈-monocarboxylic acids such asespecially lauric acid, isononanoic acid or neodecanoic acid. Thequaternization can also be performed in the presence of a Lewis acid.The quaternization can, however, also be performed in the absence of anyacid.

c) Workup of the Reaction Mixture

The reaction end product thus formed can theoretically be purifiedfurther, or the solvent can be removed. In order to improve the furtherprocessability of the products, however, it is also possible to addsolvent after the reaction, for example solvents from the Solvessoseries, 2-ethylhexanol, or essentially aliphatic solvents. Usually,however, this is not absolutely necessary, and so the reaction productis usable without further purification as an additive, optionally afterblending with further additive components (see below).

B) Further Additive Components

The fuel additized with the inventive quaternized additive is a gasolinefuel or especially a middle distillate fuel, in particular a dieselfuel.

The fuel may comprise further customary additives to improve efficacyand/or suppress wear.

In the case of diesel fuels, these are primarily customary detergentadditives, carrier oils, cold flow improvers, lubricity improvers,corrosion inhibitors, demulsifiers, dehazers, antifoams, cetane numberimprovers, combustion improvers, antioxidants or stabilizers, antistats,metallocenes, metal deactivators, dyes and/or solvents.

In the case of gasoline fuels, these are in particular lubricityimprovers (friction modifiers), corrosion inhibitors, demulsifiers,dehazers, antifoams, combustion improvers, antioxidants or stabilizers,antistats, metallocenes, metal deactivators, dyes and/or solvents.

Typical examples of suitable coadditives are listed in the followingsection:

B1) Detergent Additives

The customary detergent additives are preferably amphiphilic substanceswhich possess at least one hydrophobic hydrocarbon radical with anumber-average molecular weight (M_(a)) of 85 to 20 000 and at least onepolar moiety selected from:

-   (Da) mono- or polyamino groups having up to 6 nitrogen atoms, at    least one nitrogen atom having basic properties;-   (Db) nitro groups, optionally in combination with hydroxyl groups;-   (Dc) hydroxyl groups in combination with mono- or polyamino groups,    at least one nitrogen atom having basic properties;-   (Dd) carboxyl groups or their alkali metal or alkaline earth metal    salts;-   (De) sulfonic acid groups or their alkali metal or alkaline earth    metal salts;-   (Df) polyoxy-C₂- to C₄-alkylene moieties terminated by hydroxyl    groups, mono- or polyamino groups, at least one nitrogen atom having    basic properties, or by carbamate groups;-   (Dg) carboxylic ester groups;-   (Dh) moieties derived from succinic anhydride and having hydroxyl    and/or amino and/or amido and/or imido groups; and/or-   (Di) moieties obtained by Mannich reaction of substituted phenols    with aldehydes and mono- or polyamines.

The hydrophobic hydrocarbon radical in the above detergent additives,which ensures the adequate solubility in the fuel, has a number-averagemolecular weight (M_(n)) of 85 to 20 000, preferably of 113 to 10 000,more preferably of 300 to 5000, even more preferably of 300 to 3000,even more especially preferably of 500 to 2500 and especially of 700 to2500, in particular of 800 to 1500. As typical hydrophobic hydrocarbonradicals, especially in conjunction with the polar especiallypolypropenyl, polybutenyl and polyisobutenyl radicals with anumber-average molecular weight M_(n) of preferably in each case 300 to5000, more preferably 300 to 3000, even more preferably 500 to 2500,even more especially preferably 700 to 2500 and especially 800 to 1500into consideration.

Examples of the above groups of detergent additives include thefollowing:

Additives comprising mono- or polyamino groups (Da) are preferablypolyalkenemono- or polyalkenepolyamines based on polypropene or onhigh-reactivity (i.e. having predominantly terminal double bonds) orconventional (i.e. having predominantly internal double bonds)polybutene or polyisobutene having M_(n)=300 to 5000, more preferably500 to 2500 and especially 700 to 2500. Such additives based onhigh-reactivity polyisobutene, which can be prepared from thepolyisobutene which may comprise up to 20% by weight of n-butene unitsby hydroformylation and reductive amination with ammonia, monoamines orpolyamines such as dimethylaminopropylamine, ethylenediamine,diethylenetriamine, triethylenetetramine or tetraethylenepentamine, areknown especially from EP-A 244 616. When polybutene or polyisobutenehaving predominantly internal double bonds (usually in the β and γpositions) are used as starting materials in the preparation of theadditives, a possible preparative route is by chlorination andsubsequent amination or by oxidation of the double bond with air orozone to give the carbonyl or carboxyl compound and subsequent aminationunder reductive (hydrogenating) conditions. The amines used here for theamination may be, for example, ammonia, monoamines or the abovementionedpolyamines. Corresponding additives based on polypropene are describedin particular in WO-A 94/24231.

Further particular additives comprising monoamino groups (Da) are thehydrogenation products of the reaction products of polyisobutenes havingan average degree of polymerization P=5 to 100 with nitrogen oxides ormixtures of nitrogen oxides and oxygen, as described in particular inWO-A 97/03946.

Further particular additives comprising monoamino groups (Da) are thecompounds obtainable from polyisobutene epoxides by reaction with aminesand subsequent dehydration and reduction of the amino alcohols, asdescribed in particular in DE-A 196 20 262.

Additives comprising nitro groups (Db), optionally in combination withhydroxyl groups, are preferably reaction products of polyisobuteneshaving an average degree of polymerization P=5 to 100 or 10 to 100 withnitrogen oxides or mixtures of nitrogen oxides and oxygen, as describedin particular in WO-A 96/03367 and in WO-A 96/03479. These reactionproducts are generally mixtures of pure nitropolyisobutenes (e.g.α,β-dinitropolyisobutene) and mixed hydroxynitropolyisobutenes (e.g.α-nitro-β-hydroxypolyisobutene).

Additives comprising hydroxyl groups in combination with mono- orpolyamino groups (Dc) are in particular reaction products ofpolyisobutene epoxides obtainable from polyisobutene having preferablypredominantly terminal double bonds and M_(n)=300 to 5000, with ammoniaor mono- or polyamines, as described in particular in EP-A 476 485.

Additives comprising carboxyl groups or their alkali metal or alkalineearth metal salts (Dd) are preferably copolymers of C₂- to C₄₀-olefinswith maleic anhydride which have a total molar mass of 500 to 20 000 andsome or all of whose carboxyl groups have been converted to the alkalimetal or alkaline earth metal salts and any remainder of the carboxylgroups has been reacted with alcohols or amines. Such additives aredisclosed in particular by EP-A 307 815. Such additives serve mainly toprevent valve seat wear and can, as described in WO-A 87/01126,advantageously be used in combination with customary fuel detergentssuch as poly(iso)buteneamines or polyetheramines.

Additives comprising sulfonic acid groups or their alkali metal oralkaline earth metal salts (De) are preferably alkali metal or alkalineearth metal salts of an alkyl sulfosuccinate, as described in particularin EP-A 639 632. Such additives serve mainly to prevent valve seat wearand can be used advantageously in combination with customary fueldetergents such as poly(iso)buteneamines or polyetheramines.

Additives comprising polyoxy-C₂-C₄-alkylene moieties (Df) are preferablypolyethers or polyetheramines which are obtainable by reaction of C₂- toC₆₀-alkanols, C₆- to C₃₀-alkanediols, mono- or di-C₂- toC₃₀-alkylamines, C₁- to C₃₀-alkylcyclohexanols or C₁- toC₃₀-alkylphenols with 1 to 30 mol of ethylene oxide and/or propyleneoxide and/or butylene oxide per hydroxyl group or amino group and, inthe case of the polyetheramines, by subsequent reductive amination withammonia, monoamines or polyamines. Such products are described inparticular in EP-A 310 875, EP-A 356 725, EP-A 700 985 and U.S. Pat. No.4,877,416. In the case of polyethers, such products also have carrieroil properties. Typical examples of these are tridecanol butoxylates,isotridecanol butoxylates, isononylphenol butoxylates and polyisobutenolbutoxylates and propoxylates and also the corresponding reactionproducts with ammonia.

Additives comprising carboxylic ester groups (Dg) are preferably estersof mono-, di- or tricarboxylic acids with long-chain alkanols orpolyols, in particular those having a minimum viscosity of 2 mm²/s at100° C., as described in particular in DE-A 38 38 918. The mono-, di- ortricarboxylic acids used may be aliphatic or aromatic acids, andparticularly suitable ester alcohols or ester polyols are long-chainrepresentatives having, for example, 6 to 24 carbon atoms. Typicalrepresentatives of the esters are adipates, phthalates, isophthalates,terephthalates and trimellitates of isooctanol, of isononanol, ofisodecanol and of isotridecanol. Such products also have carrier oilproperties.

Additives comprising moieties derived from succinic anhydride and havinghydroxyl and/or amino and/or amido and/or especially imido groups (Dh)are preferably corresponding derivatives of alkyl- oralkenyl-substituted succinic anhydride and especially the correspondingderivatives of polyisobutenylsuccinic anhydride which are obtainable byreacting conventional or high-reactivity polyisobutene havingM_(n)=preferably 300 to 5000, more preferably 300 to 3000, even morepreferably 500 to 2500, even more especially preferably 700 to 2500 andespecially 800 to 1500, with maleic anhydride by a thermal route in anene reaction or via the chlorinated polyisobutene. The moieties havinghydroxyl and/or amino and/or amido and/or imido groups are, for example,carboxylic acid groups, acid amides of monoamines, acid amides of di- orpolyamines which, in addition to the amide function, also have freeamine groups, succinic acid derivatives having an acid and an amidefunction, carboximides with monoamines, carboximides with di- orpolyamines which, in addition to the imide function, also have freeamine groups, or diimides which are formed by the reaction of di- orpolyamines with two succinic acid derivatives. In the presence of imidomoieties D(h), the further detergent additive in the context of thepresent invention is, however, used only up to a maximum of 100% of theweight of compounds with betaine structure. Such fuel additives arecommon knowledge and are described, for example, in documents (1) and(2). They are preferably the reaction products of alkyl- oralkenyl-substituted succinic acids or derivatives thereof with aminesand more preferably the reaction products of polyisobutenyl-substitutedsuccinic acids or derivatives thereof with amines. Of particularinterest in this context are reaction products with aliphatic polyamines(polyalkyleneimines) such as especially ethylenediamine,diethylenetriamine, triethylenetetramine, tetraethylenepentamine,pentaethylenehexamine and hexaethyleneheptamine, which have an imidestructure.

Additives comprising moieties (Di) obtained by Mannich reaction ofsubstituted phenols with aldehydes and mono- or polyamines arepreferably reaction products of polyisobutene-substituted phenols withformaldehyde and mono- or polyamines such as ethylenediamine,diethylenetriamine, triethylenetetramine, tetraethylenepentamine ordimethylaminopropylamine. The polyisobutenyl-substituted phenols maystem from conventional or high-reactivity polyisobutene having M_(n)=300to 5000. Such “polyisobutene Mannich bases” are described in particularin EP-A 831 141.

One or more of the detergent additives mentioned can be added to thefuel in such an amount that the dosage of these detergent additives ispreferably 25 to 2500 ppm by weight, especially 75 to 1500 ppm byweight, in particular 150 to 1000 ppm by weight.

B2) Carrier Oils

Carrier oils additionally used may be of mineral or synthetic nature.Suitable mineral carrier oils are the fractions obtained in crude oilprocessing, such as brightstock or base oils having viscosities, forexample, from the SN 500 to 2000 class; but also aromatic hydrocarbons,paraffinic hydrocarbons and alkoxyalkanols. Likewise useful is afraction which is obtained in the refining of mineral oil and is knownas “hydrocrack oil” (vacuum distillate cut having a boiling range fromabout 360 to 500° C., obtainable from natural mineral oil which has beencatalytically hydrogenated and isomerized under high pressure and alsodeparaffinized). Likewise suitable are mixtures of the abovementionedmineral carrier oils.

Examples of suitable synthetic carrier oils are polyolefins(polyalphaolefins or polyinternalolefins), (poly)esters,(poly)alkoxylates, polyethers, aliphatic polyether-amines,alkylphenol-started polyethers, alkylphenol-started polyetheramines andcarboxylic esters of long-chain alkanols.

Examples of suitable polyolefins are olefin polymers having M_(n)=400 to1800, in particular based on polybutene or polyisobutene (hydrogenatedor unhydrogenated).

Examples of suitable polyethers or polyetheramines are preferablycompounds comprising polyoxy-C₂- to C₄-alkylene moieties which areobtainable by reacting C₂- to C₆₀-alkanols, C₆- to C₃₀-alkanediols,mono- or di-C₂- to C₃₀-alkylamines, C₁- to C₃₀-alkylcyclohexanols or C₁-to C₃₀-alkylphenols with 1 to 30 mol of ethylene oxide and/or propyleneoxide and/or butylene oxide per hydroxyl group or amino group, and, inthe case of the polyetheramines, by subsequent reductive amination withammonia, monoamines or polyamines. Such products are described inparticular in EP-A 310 875, EP-A 356 725, EP-A 700 985 and U.S. Pat. No.4,877,416. For example, the polyetheramines used may be poly-C₂- toC₆-alkylene oxide amines or functional derivatives thereof. Typicalexamples thereof are tridecanol butoxylates or isotridecanolbutoxylates, isononylphenol butoxylates and also polyisobutenolbutoxylates and propoxylates, and also the corresponding reactionproducts with ammonia.

Examples of carboxylic esters of long-chain alkanols are in particularesters of mono-, di- or tricarboxylic acids with long-chain alkanols orpolyols, as described in particular in DE-A 38 38 918. The mono-, di- ortricarboxylic acids used may be aliphatic or aromatic acids; suitableester alcohols or polyols are in particular long-chain representativeshaving, for example, 6 to 24 carbon atoms. Typical representatives ofthe esters are adipates, phthalates, isophthalates, terephthalates andtrimellitates of isooctanol, isononanol, isodecanol and isotridecanol,for example di(n- or isotridecyl) phthalate.

Further suitable carrier oil systems are described, for example, in DE-A38 26 608, DE-A 41 42 241, DE-A 43 09 074, EP-A 452 328 and EP-A 548617.

Examples of particularly suitable synthetic carrier oils arealcohol-started polyethers having about 5 to 35, preferably about 5 to30, more preferably 10 to 30 and especially 15 to 30 C₃- to C₆-alkyleneoxide units, for example selected from propylene oxide, n-butylene oxideand isobutylene oxide units, or mixtures thereof, per alcohol molecule.Nonlimiting examples of suitable starter alcohols are long-chainalkanols or phenols substituted by long-chain alkyl in which thelong-chain alkyl radical is in particular a straight-chain or branchedC₆- to C₁₈-alkyl radical. Particular examples include tridecanol andnonylphenol. Particularly preferred alcohol-started polyethers are thereaction products (polyetherification products) of monohydric aliphaticC₆- to C₁₈-alcohols with C₃- to C₆-alkylene oxides. Examples ofmonohydric aliphatic C₆-C₁₈-alcohols are hexanol, heptanol, octanol,2-ethylhexanol, nonyl alcohol, decanol, 3-propylheptanol, undecanol,dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol,octadecanol and the constitutional and positional isomers thereof. Thealcohols can be used either in the form of the pure isomers or in theform of technical grade mixtures. A particularly preferred alcohol istridecanol. Examples of C₃- to C₆-alkylene oxides are propylene oxide,such as 1,2-propylene oxide, butylene oxide, such as 1,2-butylene oxide,2,3-butylene oxide, isobutylene oxide or tetrahydrofuran, pentyleneoxide and hexylene oxide. Particular preference among these is given toC₃- to C₄-alkylene oxides, i.e. propylene oxide such as 1,2-propyleneoxide and butylene oxide such as 1,2-butylene oxide, 2,3-butylene oxideand isobutylene oxide. Especially butylene oxide is used.

Further suitable synthetic carrier oils are alkoxylated alkylphenols, asdescribed in DE-A 10 102 913.

Particular carrier oils are synthetic carrier oils, particularpreference being given to the above-described alcohol-startedpolyethers.

The carrier oil or the mixture of different carrier oils is added to thefuel in an amount of preferably 1 to 1000 ppm by weight, more preferablyof 10 to 500 ppm by weight and especially of 20 to 100 ppm by weight.

B3) Cold Flow Improvers

Suitable cold flow improvers are in principle all organic compoundswhich are capable of improving the flow performance of middle distillatefuels or diesel fuels under cold conditions. For the intended purpose,they must have sufficient oil solubility. In particular, useful coldflow improvers for this purpose are the cold flow improvers (middledistillate flow improvers, MDFIs) typically used in the case of middledistillates of fossil origin, i.e. in the case of customary mineraldiesel fuels. However, it is also possible to use organic compoundswhich partly or predominantly have the properties of a wax antisettlingadditive (WASA) when used in customary diesel fuels. They can also actpartly or predominantly as nucleators. It is, though, also possible touse mixtures of organic compounds effective as MDFIs and/or effective asWASAs and/or effective as nucleators.

The cold flow improver is typically selected from

(K1) copolymers of a C₂- to C₄₀-olefin with at least one furtherethylenically unsaturated monomer;

(K2) comb polymers;

(K3) polyoxyalkylenes;

(K4) polar nitrogen compounds;

(K5) sulfocarboxylic acids or sulfonic acids or derivatives thereof; and

(K6) poly(meth)acrylic esters.

It is possible to use either mixtures of different representatives fromone of the particular classes (K1) to (K6) or mixtures ofrepresentatives from different classes (K1) to (K6).

Suitable C₂- to C₄₀-olefin monomers for the copolymers of class (K1)are, for example, those having 2 to 20 and especially 2 to 10 carbonatoms, and 1 to 3 and preferably 1 or 2 carbon-carbon double bonds,especially having one carbon-carbon double bond. In the latter case, thecarbon-carbon double bond may be arranged either terminally α-olefins)or internally. However, preference is given to α-olefins, morepreferably α-olefins having 2 to 6 carbon atoms, for example propene,1-butene, 1-pentene, 1-hexene and in particular ethylene.

In the copolymers of class (K1), the at least one further ethylenicallyunsaturated monomer is preferably selected from alkenyl carboxylates,(meth)acrylic esters and further olefins.

When further olefins are also copolymerized, they are preferably higherin molecular weight than the abovementioned C₂- to C₄₀-olefin basemonomer. When, for example, the olefin base monomer used is ethylene orpropene, suitable further olefins are in particular C₁₀- toC₄₀-α-olefins. Further olefins are in most cases only additionallycopolymerized when monomers with carboxylic ester functions are alsoused.

Suitable (meth)acrylic esters are, for example, esters of (meth)acrylicacid with C₁- to C₂₀-alkanols, especially C₁- to C₁₀-alkanols, inparticular with methanol, ethanol, propanol, isopropanol, n-butanol,sec-butanol, isobutanol, tert-butanol, pentanol, hexanol, heptanol,octanol, 2-ethylhexanol, nonanol and decanol, and structural isomersthereof.

Suitable alkenyl carboxylates are, for example, C₂- to C₁₄-alkenylesters, for example the vinyl and propenyl esters, of carboxylic acidshaving 2 to 21 carbon atoms, whose hydrocarbon radical may be linear orbranched. Among these, preference is given to the vinyl esters. Amongthe carboxylic acids with a branched hydrocarbon radical, preference isgiven to those whose branch is in the α-position to the carboxyl group,the α-carbon atom more preferably being tertiary, i.e. the carboxylicacid being a so-called neocarboxylic acid. However, the hydrocarbonradical of the carboxylic acid is preferably linear.

Examples of suitable alkenyl carboxylates are vinyl acetate, vinylpropionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl neopentanoate,vinyl hexanoate, vinyl neononanoate, vinyl neodecanoate and thecorresponding propenyl esters, preference being given to the vinylesters. A particularly preferred alkenyl carboxylate is vinyl acetate;typical copolymers of group (K1) resulting therefrom are ethylene-vinylacetate copolymers (“EVAs”), which are some of the most frequently used.Ethylene-vinyl acetate copolymers usable particularly advantageously andtheir preparation are described in WO 99/29748.

Suitable copolymers of class (K1) are also those which comprise two ormore different alkenyl carboxylates in copolymerized form, which differin the alkenyl function and/or in the carboxylic acid group. Likewisesuitable are copolymers which, as well as the alkenyl carboxylate(s),comprise at least one olefin and/or at least one (meth)acrylic ester incopolymerized form.

Terpolymers of a C₂- to C₄₀-α-olefin, a C₁- to C₂₀-alkyl ester of anethylenically unsaturated monocarboxylic acid having 3 to 15 carbonatoms and a C₂- to C₁₄-alkenyl ester of a saturated monocarboxylic acidhaving 2 to 21 carbon atoms are also suitable as copolymers of class(K1). Terpolymers of this kind are described in WO 2005/054314. Atypical terpolymer of this kind is formed from ethylene, 2-ethylhexylacrylate and vinyl acetate.

The at least one or the further ethylenically unsaturated monomer(s) arecopolymerized in the copolymers of class (K1) in an amount of preferably1 to 50% by weight, especially 10 to 45% by weight and in particular 20to 40% by weight, based on the overall copolymer. The main proportion interms of weight of the monomer units in the copolymers of class (K1)therefore originates generally from the C₂ to C₄₀ base olefins.

The copolymers of class (K1) preferably have a number-average molecularweight M_(n) of 1000 to 20 000, more preferably 1000 to 10 000 and inparticular 1000 to 8000.

Typical comb polymers of component (K2) are, for example, obtainable bythe copolymerization of maleic anhydride or fumaric acid with anotherethylenically unsaturated monomer, for example with an α-olefin or anunsaturated ester, such as vinyl acetate, and subsequent esterificationof the anhydride or acid function with an alcohol having at least 10carbon atoms. Further suitable comb polymers are copolymers of α-olefinsand esterified comonomers, for example esterified copolymers of styreneand maleic anhydride or esterified copolymers of styrene and fumaricacid. Suitable comb polymers may also be polyfumarates or polymaleates.Homo- and copolymers of vinyl ethers are also suitable comb polymers.Comb polymers suitable as components of class (K2) are, for example,also those described in WO 2004/035715 and in “Comb-Like Polymers.Structure and Properties”, N. A. Platé and V. P. Shibaev, J. Poly. Sci.Macromolecular Revs. 8, pages 117 to 253 (1974)”. Mixtures of combpolymers are also suitable.

Polyoxyalkylenes suitable as components of class (K3) are, for example,polyoxyalkylene esters, polyoxyalkylene ethers, mixed polyoxyalkyleneester/ethers and mixtures thereof. These polyoxyalkylene compoundspreferably comprise at least one linear alkyl group, preferably at leasttwo linear alkyl groups, each having 10 to 30 carbon atoms and apolyoxyalkylene group having a number-average molecular weight of up to5000. Such polyoxyalkylene compounds are described, for example, in EP-A061 895 and also in U.S. Pat. No. 4,491,455. Particular polyoxyalkylenecompounds are based on polyethylene glycols and polypropylene glycolshaving a number-average molecular weight of 100 to 5000. Additionallysuitable are polyoxyalkylene mono- and diesters of fatty acids having 10to 30 carbon atoms, such as stearic acid or behenic acid.

Polar nitrogen compounds suitable as components of class (K4) may beeither ionic or nonionic and preferably have at least one substituent,in particular at least two substituents, in the form of a tertiarynitrogen atom of the general formula >NR⁷ in which R⁷ is a C₈- toC₄₀-hydrocarbon radical. The nitrogen substituents may also bequaternized, i.e. be in cationic form. An example of such nitrogencompounds is that of ammonium salts and/or amides which are obtainableby the reaction of at least one amine substituted by at least onehydrocarbon radical with a carboxylic acid having 1 to 4 carboxyl groupsor with a suitable derivative thereof. The amines preferably comprise atleast one linear C₈- to C₄₀-alkyl radical. Primary amines suitable forpreparing the polar nitrogen compounds mentioned are, for example,octylamine, nonylamine, decylamine, undecylamine, dodecylamine,tetradecylamine and the higher linear homologs. Secondary aminessuitable for this purpose are, for example, dioctadecylamine andmethylbehenylamine. Also suitable for this purpose are amine mixtures,in particular amine mixtures obtainable on the industrial scale, such asfatty amines or hydrogenated tallamines, as described, for example, inUllmann's Encyclopedia of Industrial Chemistry, 6th Edition, “Amines,aliphatic” chapter. Acids suitable for the reaction are, for example,cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid,cyclopentane-1,2-dicarboxylic acid, naphthalenedicarboxylic acid,phthalic acid, isophthalic acid, terephthalic acid, and succinic acidssubstituted by long-chain hydrocarbon radicals.

In particular, the component of class (K4) is an oil-soluble reactionproduct of poly(C₂- to C₂₀-carboxylic acids) having at least onetertiary amino group with primary or secondary amines. The poly(C₂- toC₂₀-carboxylic acids) which have at least one tertiary amino group andform the basis of this reaction product comprise preferably at least 3carboxyl groups, especially 3 to 12 and in particular 3 to 5 carboxylgroups. The carboxylic acid units in the polycarboxylic acids havepreferably 2 to 10 carbon atoms, and are especially acetic acid units.The carboxylic acid units are suitably bonded to the polycarboxylicacids, usually via one or more carbon and/or nitrogen atoms. They arepreferably attached to tertiary nitrogen atoms which, in the case of aplurality of nitrogen atoms, are bonded via hydrocarbon chains.

The component of class (K4) is preferably an oil-soluble reactionproduct based on poly(C₂- to C₂₀-carboxylic acids) which have at leastone tertiary amino group and are of the general formula IIa or IIb

in which the variable A is a straight-chain or branched C₂- toC₆-alkylene group or the moiety of the formula III

and the variable B is a C₁- to C₁₉-alkylene group. The compounds of thegeneral formulae IIa and IIb especially have the properties of a WASA.

Moreover, the preferred oil-soluble reaction product of component (K4),especially that of the general formula IIa or Ilb, is an amide, anamide-ammonium salt or an ammonium salt in which no, one or morecarboxylic acid groups have been converted to amide groups.

Straight-chain or branched C₂- to C₆-alkylene groups of the variable Aare, for example, 1,1-ethylene, 1,2-propylene, 1,3-propylene,1,2-butylene, 1,3-butylene, 1,4-butylene, 2-methyl-1,3-propylene,1,5-pentylene, 2-methyl-1,4-butylene, 2,2-dimethyl-1,3-propylene,1,6-hexylene (hexamethylene) and in particular 1,2-ethylene. Thevariable A comprises preferably 2 to 4 and especially 2 or 3 carbonatoms.

C₁- to C₁₉-alkylene groups of the variable B are, for example,1,2-ethylene, 1,3-propylene, 1,4-butylene, hexamethylene, octamethylene,decamethylene, dodecamethylene, tetradecamethylene, hexadecamethylene,octadecamethylene, nonadecamethylene and especially methylene. Thevariable B comprises preferably 1 to 10 and especially 1 to 4 carbonatoms.

The primary and secondary amines as a reaction partner for thepolycarboxylic acids to form component (K4) are typically monoamines,especially aliphatic monoamines. These primary and secondary amines maybe selected from a multitude of amines which bear hydrocarbon radicalswhich may optionally be bonded to one another.

These parent amines of the oil-soluble reaction products of component(K4) are usually secondary amines and have the general formula HN(R⁸)₂in which the two variables R⁸ are each independently straight-chain orbranched C₁₀- to C₃₀-alkyl radicals, especially C₁₄- to C₂₄-alkylradicals. These relatively long-chain alkyl radicals are preferablystraight-chain or only slightly branched. In general, the secondaryamines mentioned, with regard to their relatively long-chain alkylradicals, derive from naturally occurring fatty acid and fromderivatives thereof. The two R⁸ radicals are preferably identical.

The secondary amines mentioned may be bonded to the polycarboxylic acidsby means of amide structures or in the form of the ammonium salts; it isalso possible for only a portion to be present as amide structures andanother portion as ammonium salts. Preferably only few, if any, freeacid groups are present. The oil-soluble reaction products of component(K4) are preferably present completely in the form of the amidestructures.

Typical examples of such components (K4) are reaction products ofnitrilotriacetic acid, of ethylenediaminetetraacetic acid or ofpropylene-1,2-diaminetetraacetic acid with in each case 0.5 to 1.5 molper carboxyl group, especially 0.8 to 1.2 mol per carboxyl group, ofdioleylamine, dipalmitinamine, dicoconut fatty amine, distearylamine,dibehenylamine or especially ditallow fatty amine. A particularlypreferred component (K4) is the reaction product of 1 mol ofethylenediaminetetraacetic acid and 4 mol of hydrogenated ditallow fattyamine.

Further typical examples of component (K4) include theN,N-dialkylammonium salts of 2-N′,N′-dialkylamidobenzoates, for examplethe reaction product of 1 mol of phthalic anhydride and 2 mol ofditallow fatty amine, the latter being hydrogenated or unhydrogenated,and the reaction product of 1 mol of an alkenylspirobislactone with 2mol of a dialkylamine, for example ditallow fatty amine and/or tallowfatty amine, the last two being hydrogenated or unhydrogenated.

Further typical structure types for the component of class (K4) arecyclic compounds with tertiary amino groups or condensates of long-chainprimary or secondary amines with carboxylic acid-containing polymers, asdescribed in WO 93/18115.

Sulfocarboxylic acids, sulfonic acids or derivatives thereof which aresuitable as cold flow improvers of class (K5) are, for example, theoil-soluble carboxamides and carboxylic esters of ortho-sulfobenzoicacid, in which the sulfonic acid function is present as a sulfonate withalkyl-substituted ammonium cations, as described in EP-A 261 957.

Poly(meth)acrylic esters suitable as cold flow improvers of class (K6)are either homo- or copolymers of acrylic and methacrylic esters.Preference is given to copolymers of at least two different(meth)acrylic esters which differ with regard to the esterified alcohol.The copolymer optionally comprises another different olefinicallyunsaturated monomer in copolymerized form. The weight-average molecularweight of the polymer is preferably 50 000 to 500 000. A particularlypreferred polymer is a copolymer of methacrylic acid and methacrylicesters of saturated 014 and 015 alcohols, the acid groups having beenneutralized with hydrogenated tallamine. Suitable poly(meth)acrylicesters are described, for example, in WO 00/44857.

The cold flow improver or the mixture of different cold flow improversis added to the middle distillate fuel or diesel fuel in a total amountof preferably 10 to 5000 ppm by weight, more preferably of 20 to 2000ppm by weight, even more preferably of 50 to 1000 ppm by weight andespecially of 100 to 700 ppm by weight, for example of 200 to 500 ppm byweight.

B4) Lubricity Improvers

Suitable lubricity improvers or friction modifiers are based typicallyon fatty acids or fatty acid esters. Typical examples are tall oil fattyacid, as described, for example, in WO 98/004656, and glycerylmonooleate. The reaction products, described in U.S. Pat. No. 6,743,266B2, of natural or synthetic oils, for example triglycerides, andalkanolamines are also suitable as such lubricity improvers.

B5) Corrosion Inhibitors

Suitable corrosion inhibitors are, for example, succinic esters, inparticular with polyols, fatty acid derivatives, for example oleicesters, oligomerized fatty acids, substituted ethanolamines, andproducts sold under the trade name RC 4801 (Rhein Chemie Mannheim,Germany) or HiTEC 536 (Ethyl Corporation).

B6) Demulsifiers

Suitable demulsifiers are, for example, the alkali metal or alkalineearth metal salts of alkyl-substituted phenol- and naphthalenesulfonatesand the alkali metal or alkaline earth metal salts of fatty acids, andalso neutral compounds such as alcohol alkoxylates, e.g. alcoholethoxylates, phenol alkoxylates, e.g. tert-butylphenol ethoxylate ortert-pentylphenol ethoxylate, fatty acids, alkylphenols, condensationproducts of ethylene oxide (EO) and propylene oxide (PO), for exampleincluding in the form of EO/PO block copolymers, polyethyleneimines orelse polysiloxanes.

B7) Dehazers

Suitable dehazers are, for example, alkoxylated phenol-formaldehydecondensates, for example the products available under the trade namesNALCO 7D07 (Nalco) and TOLAD 2683 (Petrolite).

B8) Antifoams

Suitable antifoams are, for example, polyether-modified polysiloxanes,for example the products available under the trade names TEGOPREN 5851(Goldschmidt), Q 25907 (Dow Corning) and RHODOSIL (Rhone Poulenc).

B9) Cetane Number Improvers

Suitable cetane number improvers are, for example, aliphatic nitratessuch as 2-ethylhexyl nitrate and cyclohexyl nitrate and peroxides suchas di-tert-butyl peroxide.

B10) Antioxidants

Suitable antioxidants are, for example substituted phenols, such as2,6-di-tert-butylphenol and 6-di-tert-butyl-3-methylphenol, and alsophenylenediamines such as N,N′-di-sec-butyl-p-phenylenediamine.

B11) Metal Deactivators

Suitable metal deactivators are, for example, salicylic acid derivativessuch as N,N′-disalicylidene-1,2-propanediamine.

B12) Solvents

Suitable solvents are, for example, nonpolar organic solvents such asaromatic and aliphatic hydrocarbons, for example toluene, xylenes, whitespirit and products sold under the trade names SHELLSOL (RoyalDutch/Shell Group) and EXXSOL (ExxonMobil), and also polar organicsolvents, for example, alcohols such as 2-ethylhexanol, decanol andisotridecanol. Such solvents are usually added to the diesel fueltogether with the aforementioned additives and coadditives, which theyare intended to dissolve or dilute for better handling.

C) Fuels

The inventive additive is outstandingly suitable as a fuel additive andcan be used in principle in any fuels. It brings about a whole series ofadvantageous effects in the operation of internal combustion engineswith fuels. Preference is given to using the inventive quaternizedadditive in middle distillate fuels, especially diesel fuels.

The present invention therefore also provides fuels, especially middledistillate fuels, with a content of the inventive quaternized additivewhich is effective as an additive for achieving advantageous effects inthe operation of internal combustion engines, for example of dieselengines, especially of direct-injection diesel engines, in particular ofdiesel engines with common-rail injection systems. This effectivecontent (dosage) is generally 10 to 5000 ppm by weight, preferably 20 to1500 ppm by weight, especially 25 to 1000 ppm by weight, in particular30 to 750 ppm by weight, based in each case on the total amount of fuel.

Middle distillate fuels such as diesel fuels or heating oils arepreferably mineral oil raffinates which typically have a boiling rangefrom 100 to 400° C. These are usually distillates having a 95% point upto 360° C. or even higher. These may also be so-called “ultra low sulfurdiesel” or “city diesel”, characterized by a 95% point of, for example,not more than 345° C. and a sulfur content of not more than 0.005% byweight or by a 95% point of, for example, 285° C. and a sulfur contentof not more than 0.001% by weight. In addition to the mineral middledistillate fuels or diesel fuels obtainable by refining, thoseobtainable by coal gasification or gas liquefaction [“gas to liquid”(GTL) fuels] or by biomass liquefaction [“biomass to liquid” (BTL)fuels] are also suitable. Also suitable are mixtures of theaforementioned middle distillate fuels or diesel fuels with renewablefuels, such as biodiesel or bioethanol.

The qualities of the heating oils and diesel fuels are laid down indetail, for example, in DIN 51603 and EN 590 (cf. also Ullmann'sEncyclopedia of Industrial Chemistry, 5th edition, Volume A12, p. 617ff.).

In addition to the use thereof in the abovementioned middle distillatefuels of fossil, vegetable or animal origin, which are essentiallyhydrocarbon mixtures, the inventive quaternized additive can also beused in mixtures of such middle distillates with biofuel oils(biodiesel). Such mixtures are also encompassed by the term “middledistillate fuel” in the context of the present invention. They arecommercially available and usually comprise the biofuel oils in minoramounts, typically in amounts of 1 to 30% by weight, especially of 3 to10% by weight, based on the total amount of middle distillate of fossil,vegetable or animal origin and biofuel oil.

Biofuel oils are generally based on fatty acid esters, preferablyessentially on alkyl esters of fatty acids which derive from vegetableand/or animal oils and/or fats. Alkyl esters are typically understood tomean lower alkyl esters, especially C₁-C₄-alkyl esters, which areobtainable by transesterifying the glycerides which occur in vegetableand/or animal oils and/or fats, especially triglycerides, by means oflower alcohols, for example ethanol or in particular methanol (“FAME”).Typical lower alkyl esters based on vegetable and/or animal oils and/orfats, which find use as a biofuel oil or components thereof, are, forexample, sunflower methyl ester, palm oil methyl ester (“PME”), soya oilmethyl ester (“SME”) and especially rapeseed oil methyl ester (“RME”).

The middle distillate fuels or diesel fuels are more preferably thosehaving a low sulfur content, i.e. having a sulfur content of less than0.05% by weight, preferably of less than 0.02% by weight, moreparticularly of less than 0.005% by weight and especially of less than0.001% by weight of sulfur.

Useful gasoline fuels include all commercial gasoline fuel compositions.One typical representative which shall be mentioned here is theEurosuper base fuel to EN 228, which is customary on the market. Inaddition, gasoline fuel compositions of the specification according toWO 00/47698 are also possible fields of use for the present invention.

The inventive quaternized additive is especially suitable as a fueladditive in fuel compositions, especially in diesel fuels, forovercoming the problems outlined at the outset in direct-injectiondiesel engines, in particular in those with common-rail injectionsystems.

The invention is now illustrated in detail by the working examples whichfollow. The test methods described herein are not restricted to thespecific working examples, but are part of the general disclosure of thedescription and can be employed generally in the context of the presentinvention.

EXPERIMENTAL SECTION A. General Test Methods

Engine Test

b1) XUD9 test—determination of flow restriction

The procedure was according to the standard stipulations of CEC F-23-01.

b2) DW10—keep clean test

To examine the influence of the inventive compounds on the performanceof direct-injection diesel engines, the power loss was determined on thebasis of the official test method CEC F-098-08. The power loss is adirect measure of formation of deposits in the injectors.

The keep clean test is based on CEC test procedure F-098-08 Issue 5. Thesame test setup and engine type (PEUGEOT DW10) as in the CEC procedureare used.

Special Features of the Test Used:

a) Injectors

in the tests, cleaned injectors were used. The cleaning time in anultrasound bath in water at 60° C.+10% Superdecontamine (Intersciences,Brussels) was 4 h.

b) Test Run Times

the test period was 12 h without shutdown phases. The one-hour testcycle (see table below) from CEC F-098-08 was run through 12 times.

Charge air temperature Engine speed Torque downstream of Duration (rpm)Load (Nm) charge run cooler Stage (minutes) +/−20 (%) +/−5 (° C.) +/−3 12 1750 (20) 62 45 2 7 3000 (60) 173  50 3 2 1750 (20) 62 45 4 7 3500(80) 212  50 5 2 1750 (20) 62 45 6 10 4000 100  * 50 7 2 1250 (10) 25 43** 8 7 3000 100  * 50 9 2 1250 (10) 25  43** 10 10 2000 100  * 50 112 1250 (10) 25  43** 12 7 4000 100  * 50 Σ = 1 h * for range to beexpected see CEC-098-08 **target value

c) Power Determination

The initial power (P₀, KC [kW]) is calculated from the measured torqueat full load 4000/min directly after the test has started and the enginehas warmed up. The procedure is described in Issue 5 of the testprocedure CEC F-98-08. The same test setup and the PEUGEOT DW10 enginetype are used.

The final power (P_(end), end, KC) is determined in the 12th cycle instage 12, (see table above). Here too, the operating point is full load4000/min. P_(end), KC [kW] is calculated from the measured torque.

The power loss in KC is calculated as follows:

power loss,KC[%]=(1−P _(end) ,KC/P ₀ ,KC)×100

The fuel used was a commercial diesel fuel from Halternann (RF-06-03).To synthetically induce the formation of deposits at the injectors, 1ppm of zinc was added thereto in the form of a zinc neodecanoatesolution.

B. Preparation Examples Reactants Used

PIBSA: Prepared from maleic anhydride and PIB 1000 in a known manner.For the inventive preparation examples and comparative examples whichfollow, qualities with hydrolysis numbers in the region of 84-95 mgKOH/g were used. DMAPA was used with the particular PIBSA quality in amolar ratio of 1:1 according to the hydrolysis number. The PIBSAqualities used had bismaleation levels (BML) of less than 15%.

DMAPA: M=102.18

methyl salicylate: M=152.14

dimethyl phthalate: M=194.19

dimethyl oxalate: M=118.09

dimethyl sulfate: M=126.13

dimethyl carbonate M=90.08

Preparation Example 1 Synthesis of an Inventive Quaternized Succinimide(PIBSA/DMAPA/dimethyl phthalate)

Polyisobutylenesuccinic anhydride (1659 g) is dissolved in SolventNaphtha Heavy (SNH, Exxon Mobil, CAS64742-95-5) (1220 g), and3-dimethylamino-1-propylamine (DMAPA; 153 g) is added. The reactionsolution is stirred at 170° C. for 8 h, in the course of which water ofcondensation formed is distilled off continuously. This affords thePIBSA-DMAPA succinimide as a solution in Solvent Naphtha Heavy (TBN0.557 mmol/g).

A portion of this solution of the PIBSA-DMAPA succinimide (181 g) isadded to dimethyl phthalate (19.4 g), and the resulting reactionsolution is stirred at 120° C. for 11 h and then at 150° C. for 24 h.After cooling to room temperature, the product obtained is the ammoniumcarboxylate as a solution in Solvent Naphtha Heavy. ¹H NMR analysisconfirms the quaternization.

Preparation Example 2 Synthesis of an Inventive Quaternized Succinimide(PIBSA/DMAPA/methyl salicylate)

Polyisobutylenesuccinic anhydride (PIBSA; 2198 g) is heated to 110° C.,and 3-dimethylamino-1-propylamine (DMAPA; 182 g) is added within 40 min,in the course of which the reaction mixture heats up to 140° C. Thereaction mixture is heated to 170° C. and held at this temperature for 3h, in the course of which 28 g of distillate are collected. This affordsthe PIBSA-DMAPA succinimide as a viscous oil (TBN 0.735 mmol/g).

A mixture of this PIBSA-DMAPA succinimide (284.5 g), methyl salicylate(65.5 g) (i.e. about 2 equivalents of methyl salicylate per equivalentof tertiary amino group) and 3,3,5-trimethylheptanoic acid (from BASF)(0.75 g) is heated to 140-150° and the reaction mixture is stirred atthis temperature for 6 h. After cooling to room temperature, the productobtained is the ammonium salicylate as a viscous oil. ¹H NMR analysisconfirms the quaternization. By adding Pilot 900 oil, Petrochem CarlessLtd., the active ingredient content of the solution is adjusted to 50%by weight.

Preparation Example 3 Synthesis of an Inventive Quaternized Succinimide(PIBSA/DMAPA/dimethyl oxalate)

Polyisobutylenesuccinic anhydride (PIBSA; 2198 g) is heated to 110° C.,and 3-dimethylamino-1-propylamine (DMAPA; 182 g) is added within 40 min,in the course of which the reaction mixture heats up to 140° C. Thereaction mixture is heated to 170° C. and held at this temperature for 3h, in the course of which 28 g of distillate are collected. This affordsthe PIBSA-DMAPA succinimide as a viscous oil (TBN 0.735 mmol/g).

A mixture of this PIBSA-DMAPA succinimide (211 g), dimethyl oxalate(34.5 g) and lauric acid (4.9 g) is heated to 120° C. and then stirredat this temperature for 4 h. Excess dimethyl oxalate is removed on arotary evaporator under reduced pressure (p=5 mbar) at 120° C. Theproduct obtained is the ammonium methyl oxalate as a viscous oil. ¹H NMRanalysis confirms the quaternization.

For comparison with the prior art, Examples 2 and 4 from WO 2006/135881were worked up.

Preparation Example 4 Synthesis of a Known Quaternized Succinimide(Comparative Example) (Example 2 from WO 2006/135881)

A solution of PIBSA (420.2 g) in Pilot 900 oil, Petrochem Carless Ltd.,(51.3 g) is initially charged and heated to 110° C. DMAPA (31.4 g) ismetered in within 50 minutes, in the course of which a slightlyexothermic reaction is observed. Within 80 minutes, the reaction mixtureis heated to 150° C. and the mixture is then kept at this temperaturefor 3 h, in the course of which the water of reaction which forms isdistilled off. After cooling to room temperature, the PIBSA-DMAPAsuccinimide is obtained as a solution in Pilot 900 oil (TBN 0.62mmol/g).

A portion of the PIBSA-DMAPA succinimide thus obtained as a solution inPilot 900 oil, Petrochem Carless Ltd., (354 g) is initially charged andheated to 90° C. Dimethyl sulfate (26.3 g) is metered in, in the courseof which the reaction temperature rises to 112° C. Subsequently, thereaction mixture is stirred at 100° C. for 3 h. After cooling to roomtemperature, the quaternized PIBSA-DMAPA succinimide is obtained as asolution in Pilot 900 oil. ¹H NMR confirmed the quaternization. Theoutput was adjusted to an active ingredient content of 50% by weight byadding Pilot 900 oil.

Preparation Example 5 Synthesis of a Known Quaternized Succinimide(Comparative Example) (Example 4 from WO 2006/135881)

A solution of PIBSA (420.2 g) in Pilot 900 oil, Petrochem Carless Ltd.,(51.3 g) is initially charged and heated to 110° C. DMAPA (31.4 g) ismetered in within 50 minutes, in the course of which a slightlyexothermic reaction is observed. Within 80 minutes, the reaction mixtureis heated to 150° C. and the mixture is then kept at this temperaturefor 3 h, in the course of which the water of reaction which forms isdistilled off. After cooling to room temperature, the PIBSA-DMAPAsuccinimide is obtained as a solution in Pilot 900 oil (TBN 0.62mmol/g).

A portion of the PIBSA-DMAPA succinimide thus obtained as a solution inPilot 900 oil, Petrochem Carless Ltd., (130 g), dimethyl carbonate (20g) and methanol (17.4) are charged into an autoclave and inertized withnitrogen, and a starting pressure of 1.3 bar is established.Subsequently, the reaction mixture is stirred under autogenous pressurefirst at 90° C. for 1 h, then at 140° C. for 24 h. After cooling to roomtemperature, the autoclave is decompressed and the contents are rinsedout completely with a little toluene as a solvent. All low-boilingconstituents are subsequently removed on a rotary evaporator underreduced pressure to obtain the quaternized PIBSA-DMAPA succinimide as asolution in Pilot 900 oil. ¹H NMR analysis confirmed the partialquaternization. The output is adjusted to an active ingredient contentof 50% by weight by adding Pilot 900 oil.

C. Use Examples

In the use examples which follow, the additives are used either as apure substance (as synthesized in the above preparation examples) or inthe form of an additive package.

-   M1: Additive according to preparation example 2 (inventive,    quaternized with methyl salicylate)-   M2: Additive according to preparation example 4 (comparative,    quaternized with dimethyl sulfate)-   M3: Additive according to preparation example 5 (comparative,    quaternized with dimethyl carbonate)

Use Example 1 Determination of the Additive Action on the Formation ofDeposits in Diesel Engine Injection Nozzles

a) XUD9 Tests

Fuel used: RF-06-03 (reference diesel, Halternann Products, Hamburg)

The results are compiled in table 1:

TABLE 1 XUD9 tests Dosage according to Flow restriction preparationexample 0.1 mm needle Ex. Name [mg/kg] stroke [%] #1 M1, according to 3010.7 preparation example 2 #2 M2, according to 30 48.5 preparationexample 4 #3 M3, according to 30 20.8 preparation example 5

It was found that the inventive additive M1, with the same dosage, hasan improved effect compared to the prior art (M2, M3).

b) DW10 Test

To study the influence of the inventive compound on the performance ofdirect-injection diesel engines, the power loss was determined based onthe official test method CEC F-098-08 as described above. The power lossis a direct measure of formation of deposits in the injectors. Aconventional direct-injection diesel engine with a common-rail systemwas used.

The fuel used was a commercial diesel fuel from Halternann (RF-06-03).To synthetically induce the formation of deposits at the injectors, 1ppm by weight of zinc in the form of a zinc didodecanoate solution wasadded thereto.

The table below shows the results of the determinations of the relativepower loss at 4000 rpm after 12 hours of sustained operation withoutinterruption. The value P₀ gives the power after 10 minutes and thevalue P_(end) the power at the end of the measurement:

The test results are shown in table 2.

TABLE 2 Results of the DW10 test Dose Time P₀ P_(end) Additive [mg/kg][h] [KW] [KW] Power loss Base value 0 12 99.3 94.3 5.0% M1, according topreparation 160 12 98.7 97.4 1.32%  example 2 M2, according topreparation 160 12 99 98.1 0.9% example 4 M3, according to preparation160 12 98.1 95.7 2.4% example 5

It was found that the inventive additive M1 has an improved effectcompared to the base value and has an improved effect at least comparedto example M3.

Use Example 2 Determination of the Solubility Properties

To determine the solubility properties, the following additive packageswere produced and tested:

M 4 (inventive) Substance Content [ppm] Additive acc. to preparationexample 2 160.00 Dehazer, commercial 3.00 Antifoam, silicone-based,commercial 6.00 Solvent Naphtha Heavy 80.00 Total 249.00

M 5 (comparative, dimethyl sulfate) Substance Content [ppm] Additiveacc. to preparation example 4 160.00 Dehazer, commercial 3.00 Antifoam,silicone-based, commercial 6.00 Solvent Naphtha Heavy 420.00 Total589.00

M 6 (comparative, dimethyl carbonate) Substance Content [ppm] Additiveacc. to preparation example 5 160.00 Dehazer (commercial) 3.00 Antifoam,silicone-based, commercial 6.00 Solvent Naphtha Heavy 150.00 Total319.00

The result of the solubility tests is compiled in the table below. Theminimum amount of solvent (Solvent Naphtha Heavy) needed to obtain ahomogeneous, clear diesel performance package at room temperature withotherwise identical amounts of active substance, Pilot 900, antifoam anddehazer is reported.

TABLE 3 Determination of the solvent requirement Minimum amount ofAdditive solvent needed for a Additive package homogeneous packagePIBSA-DMAPA-imide-methyl M4 32% salicylate PIBSA-DMAPA-imide-dimethyl M571% sulfate PIBSA-DMAPA-imide-dimethyl M6 47% carbonate

It was found that, surprisingly, the additive according to preparationexample 2 has the best solubility properties, i.e. requires the leastsolvent.

Reference is made explicitly to the disclosure of the publications citedherein.

1. A fuel composition comprising, in a majority of a customary fuel, aproportion of at least one reaction product comprising a quaternizednitrogen compound, or a fraction thereof which comprises a quaternizednitrogen compound and is obtained from the reaction product bypurification, said reaction product being obtainable by a) reacting ahydrocarbyl-substituted polycarboxylic acid compound with a compoundcomprising at least one oxygen or nitrogen group reactive, especiallycapable of addition or condensation, with the polycarboxylic acid, andcomprising at least one quaternizable amino group, to obtain aquaternizable hydrocarbyl-substituted polycarboxylic acid compound, andb) subsequent reaction thereof with a quaternizing agent which convertsthe at least one quaternizable amino group to a quaternary ammoniumgroup, said quaternizing agent being the alkyl ester of a cycloaromaticor cycloaliphatic mono- or polycarboxylic acid, especially of a mono- ordicarboxylic acid, or of an aliphatic polycarboxylic acid, especiallydicarboxylic acid.
 2. A fuel composition comprising, in a majority of acustomary fuel, a proportion of at least one reaction product comprisinga quaternized nitrogen compound, or a fraction thereof which comprises aquaternized nitrogen compound and is obtained from the reaction productby purification, said reaction product being obtainable by reacting aquaternizable hydrocarbyl-substituted polycarboxylic acid compoundcomprising at least one quaternizable amino group with a quaternizingagent which converts the at least one quaternizable amino group to aquaternary ammonium group, said quaternizing agent being the alkyl esterof a cycloaromatic or cycloaliphatic mono- or polycarboxylic acid,especially of a mono- or dicarboxylic acid, or of an aliphaticpolycarboxylic acid, especially dicarboxylic acid.
 3. The fuelcomposition according to either of the preceding claims, wherein about1.1 to about 2.0 or about 1.25 to about 2.0 equivalents of quaternizingagent are used per equivalent of quaternizable tertiary nitrogen atom.4. The fuel composition according to any of the preceding claims,wherein the hydrocarbyl-substituted polycarboxylic acid compound is apolyisobutenylsuccinic acid or an anhydride thereof, said acid having abismaleation level of less than about 20% or less than about 15%.
 5. Thefuel composition according to any of the preceding claims, wherein thequaternizing agent is a compound of the general formula 1R₁OC(O)R₂  (1) in which R₁ is a lower alkyl radical and R₂ is anoptionally substituted monocyclic aryl or cycloalkyl radical, where thesubstituent is selected from OH, NH₂, NO₂, C(O)OR₃, and R₁OC(O)—, inwhich R₁ is as defined above and R₃ is H or R₁.
 6. The fuel compositionaccording to any of the preceding claims, wherein the quaternizing agentis a compound of the general formula 2R₁OC(O)-A-C(O)OR_(1a)  (2) in which R₁ and R_(1a) are each independentlya lower alkyl radical and A is hydrocarbylene, such as especiallyalkylene or alkenylene.
 7. The fuel composition according to any of thepreceding claims, wherein the quaternized nitrogen compound has anumber-average molecular weight in the range from 500 to 5000,especially 800 to 3000 or 900 to
 1500. 8. The fuel composition accordingto any of the preceding claims, wherein the quaternizing agent isselected from alkyl salicylates, dialkyl phthalates and dialkyloxalates.
 9. The fuel composition according to claim 1, wherein thecompound which is reactive, especially capable of addition orcondensation, with the polycarboxylic acid and comprises an oxygen ornitrogen group and at least one quaternizable amino group is selectedfrom a) hydroxyalkyl-substituted mono- or polyamines having at least onequaternizable primary, secondary or tertiary amino group; b)straight-chain or branched, cyclic, heterocyclic, aromatic ornonaromatic polyamines having at least one primary or secondary aminogroup and having at least one quaternizable primary, secondary ortertiary amino group; c) piperazines.
 10. The fuel composition accordingto claim 9, wherein the compound which is reactive, especially capableof addition or condensation, with the polycarboxylic acid and comprisesan oxygen or nitrogen group and at least one quaternizable amino groupis selected from a) hydroxyalkyl-substituted primary, secondary ortertiary monoamines and hydroxyalkyl-substituted primary, secondary ortertiary diamines, b) straight-chain or branched aliphatic diamineshaving two primary amino groups; di- or polyamines having at least oneprimary and at least one secondary amino group; di- or polyamines havingat least one primary and at least one tertiary amino group; aromaticcarbocyclic diamines having two primary amino groups; aromaticheterocyclic polyamines having two primary amino groups; aromatic ornonaromatic heterocycles having one primary and one tertiary aminogroup.
 11. The fuel composition according to any of the precedingclaims, selected from diesel fuels, biodiesel fuels, gasoline fuels andalkanol-containing gasoline fuels.
 12. A reaction product obtainable bya process as defined in any of the preceding claims or quaternizablenitrogen compound obtained from the reaction product.
 13. A process forpreparing a quaternized nitrogen compound according to claim 12,comprising the reaction of a quaternizable hydrocarbyl-substitutedpolycarboxylic acid compound comprising at least one tertiaryquaternizable amino group with a quaternizing agent which converts theat least one tertiary amino group to a quaternary ammonium group, saidquaternizing agent being the alkyl ester of a cycloaromatic orcycloaliphatic mono- or polycarboxylic acid, especially of a mono- ordicarboxylic acid, or of an aliphatic polycarboxylic acid, especiallydicarboxylic acid.
 14. The use of a reaction product or of a quaternizednitrogen compound according to claim 12 or of a compound preparedaccording to claim 13 as a fuel additive.
 15. The use according to claim14 as an additive for reducing the fuel consumption of direct-injectiondiesel engines, especially of diesel engines with common-rail injectionsystems, and/or for minimizing power loss in direct-injection dieselengines, especially in diesel engines with common-rail injectionsystems.
 16. The use according to claim 14 as a gasoline fuel additivefor reducing the level of deposits in the intake system of a gasolineengine, such as especially DISI (direct injection spark ignition) andPFI (port fuel injector) engines.
 17. The use according to claim 14 as adiesel fuel additive, especially as a cold flow improver, as a waxantisettling additive (WASA) or as an additive for reducing the level ofand/or preventing deposits in the intake systems, such as especially theinternal diesel injector deposits (IDIDs), and/or valve sticking indirect-injection diesel engines, especially in common-rail injectionsystems.
 18. An additive concentrate comprising, in combination withfurther diesel fuel or gasoline fuel additives, especially diesel fueladditives, at least one quaternized nitrogen compound as defined inclaim 12 or prepared according to claim 13.